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PARASITES AND PARASITOSIS OF THE 
DOMESTIC ANIMALS 



THE MACMILLAN COMPANY 



MACMILLAN & CO., Limited 



THE MACMILLAN CO. OF CANADA, Ltd. 

TORONTO 



PARASITES AND PARASITOSIS 

OF THE 

DOMESTIC ANIMALS 



THE ZOOLOGY AND CONTROL OF THE ANIMAL 

PARASITES AND THE PATHOGENESIS AND 

TREATMENT OF PARASITIC DISEASES 



BY 

B.' M. UNDERHILL, V.M.D. 

PROFESSOR OF PARASITOLOGY AND INSTRUCTOR IN ZOOLOGY AND 

HISTOLOGY, SCHOOL OF VETERINARY MEDICINE, UNm)R- 

SITY OP PENNSYLVANIA, ZOftLOGIST, DIVISION OF 

LABORATORIES, PENNSYLVANIA STATE 

BUREAU OF ANIJIAL INDUSTRY 



WITH 180 ILLUSTRATIONS 



THE MACMILLAN COMPANY 
1920 

All rights reserved 






COPYBIQHT, 1920 

By the MACMILLAN COMPANY 



Set up and printed. Published April, 1920 



JUN -2 1920 



r.!A571l75 



^\0 1 



PREFACE 

In the preparation of this worlv the autlior has aimed to present 
clearty, concisely, and in orderly manner such matter pertaining to the 
subject at hand as seems most essential to the needs of the student and 
the practitioner. Notwithstanding its elementary character, the present 
rapid advances in parasitology have necessitated numerous changes and 
additions to the manuscript during its preparation. New species and 
unsettling facts and theories as to some which are not new are, in these 
days of intensive research, frequently being brought to light and re- 
ported upon. Some of these findings represent or lead to a distinct 
advance and, though the observations be in certain cases upon obscure 
and in themselves imimportant species, thej'' may, by analogy, shed 
valuable light upon life histories and modes of infection of related forms 
known to be injurious to domestic animals and man. So frequent are 
these steps forward that it might almost seem better to leave compara- 
tive parasitology at the present time to the fragmental attention it has 
mainly received, and possibly it is to this view that the lack of a recent 
American volume upon the subject may be attributed. Be that as it 
may, this book is not intended to be comprehensive, and it contains but 
little discussion, historical or otherwise, of iirvestigations in the field of 
medical zoology, — limitations which may, in measure, contribute to it a 
longer period of usefulness in its present form than could be hoped for 
in an exhaustive treatise. With but few exceptions, the parasites con- 
sidered are those most likely to be met with and as to which most of the 
facts pertaining to their iDiolbgy and pathogenicity have been well 
established. 

The treatment of the subject is based upon the advantages of pre- 
senting it with at least a rudimental attention to the biologic principles 
involved in parasitism, a loiowledge of which is requisite to the proper 
conception of parasitology and certainly essential to intelligently 
applied measures of control. The direct and lucid style of the text 
throughout will, it is hoped, bring these briefly' considered fundamentals 
before the reader in their true Isearing upon the whole subject and render 
the book particularly acceptable to the general practitioner as well as to 
the student. 

Teachers will appreciate that laboratory work should supplement the 
class-room method of stud\'. Of course the student should in ever\' 
case see the parasite under consideration in so far as this is possible. 
Metiiods of laboratory technique and \\\o selection of type speciniens for 



vi PREFACE 

dissection should, in the author's opinion, be left to the teacher, who 
should certainly be the one best qualified to fornuilate the course adapted 
to liis needs. No general outline, therefore, as to laboratory methods 
has been attempted. 

If, as has been said, oiiginality is not the best recommendation for a 
work of this kind, the author feels quite sure that its defects cannot to 
any great extent be attributed to that source. His observations in the 
field and laboratorj^ have been utilized in the preparation of the book, 
but contribute nothing to its pages that is advanced or aggressively 
critical. Excluding. the first three chapters, so much of the subject- 
matter has been drawn from the published results of the labors of others 
that the numerous sources cannot well be enumerated here. Acknowl- 
edgments are especially due to bulletins and articles upon various topics 
of parasitology written by workers in federal and state bureaus of ex- 
perimental research. Other sources which have been relied upon and 
freely used are: M. Neveu-Lemaire's Parasitologic des Animaux Domes- 
tiques; Herms' Medical and Veterinary Entomology; Riley and Johann- 
sen's Handbook of Medical Entomology; Calkins' Protozoology; Neumann's 
Parasites and Parasitic Diseases of the Domesticated Animals; Braun's 
Animal Parasites of Man; The Journal of Parasitology; The American 
Edition of Hutyra and Marek, and Osborn's Economic Zoology. 

The author wishes to ex])ress his sincere ajspreciation and thanks to 
his iaboratoiy coworker, Dr. Fred Boerner, Jr., for his assistance in the 
collection of specimens and in the examination of pathologic material; 
also to Dr. William J. Lenfz for his reading and valuable criticism of 
parts of the manuscript, and to Dr. C. P. Fitch for his helpful suggestions 
as to sources of reference. 

Illustrations for a work of this character will be an aid to the text in 
proportion as they are exact and well chosen. For the study of mor- 
phologic characteristics photographs of actual specimens are often too 
obsciu-e in detail, and accurate drawings or line sketches are, as a rule, of 
greater service. It will be observed that many of the figures in this 
book are taken from publications issued by the United States Depart- 
ment of Agi'iculture. Probably no better drawings of these subjects have 
been produced, and the jjrivilege granted to use them is esteemed as a 
helpful favor of much value to the work. In this connection the author 
would especially express his gratitude to Dr. L. 0. Howard, Chief of the 
Bureau of Entomology, to Dr. John R. IMohler, Chief of the Bureau of 
Animal Industry, to Dr. Herbert Osborn, to Dr. Howard Crawley, and 
to Dr. B. H. Ransom. Finally, thanks are due to Dr. W. H. Hoedt of 
Philadelphia, for his skill and interest in preparing the photomicro- 
graphs and manj- of the drawings. 

B. M. U. 

Philadelphia, Pa. 



CONTENTS 
PART I 

PRELIMINARY CHAPTERS 
THE EXTERNAL PARASITES 



CHAPTER I 

PAPE 

Introduction 1 

Origin of pai-asitism; Influences inhibiting organic multiplication; The 
struggle for existence; The sheltered mode of life; Its effect; Phases of the 
symbiotic relationship; Example of mutualism; Examples of oommensalism; 
True parasitism; Adaptive and degenerative modifications of the parasite; 
Faculties of parasitic and predatory animals compared; Simplicity, primitive 
and degnerative; The Tunioata; Functions involved in adaptation to para- 
sitism; The reproductive process in Melophagus ovinus; Development ol the 
reproductive function in parasites; Parasitism of Gastrophilus iniestinalis; 
Alternation of hosts in life cycle of parasites; The complicated cycle of the 
liver fluke; The tapewoi-m as an example of extreme parasitism; Deductions 
as to the systematic position of pai-asites through comparison with free-living 
forms. 

CHAPTER II 

Forms of Parasitism and Influence upon the Host 7 

Terms used in parasitology; S3anbiosis; Mutualism; Commensalism; 
Helotism; Parasitism; Phytoparasites; Zooparasites; Optional occasional 
parasites; Obligate occasional parasites; Determinate transitory parasites; 
Permanent parasites; Fixed parasites; Erratic parasites; Determinate 
erratic parasites; Monoxenous parasites; Heteroxenous parasites; Trans- 
migration; Incidental or stray parasites; Ectoparasites; Entoparasites; 
Helminthes; Temis used in the designation of parasitic diseases; Preda- 
cious and parasitic animals; Factors governing injury to the host by para- 
sites; General etiologic factors. 

CHAPTER III 

Phulum I. Arthropoda 13 

Characteristics of the Arthropoda; Characteristics of the class Insecta; 
Insect methods of reproduction; Duration of life of insects. 



viii CONTENTS 

CHAPTER IV 

PAGE 

Mosquitoes ant) Gnats 23 

Characteristics of the order Diptera; Dipterous parasitism; Charactis- 
tics of the family Culicida?; Range and prevalence of mosquitoes; Their 
breeding habits; Theu- pathologic importance; The transmitter of malaria; 
Methods of distinguishing between Anopheles and Culex; The transmitter of 
yellow fever; Characteristics and habits of the species Ades calojms; Effect 
of mosquitoes upon live stock; Mosquito control; Characteristics of the 
family Simuliidse; The Southern buffalo gnat; Effect of its attack upon live 
stock; Control; Protection and treatment. 

CHAPTER ^• 

The Flies 35 

Characteristics of the family Tabanidce; Horse-flies; Gad-flies; Effect of 
their attack; Protection; Characteristics of the family Muscidae; The 
house-fly; Habits of the house-fly and its relation to the transmission of 
disease; Its control; Protective measures; The horn fly; Its habits; Effect of 
its attack; Its control; The tsetse flies; Characteristics of the genus Glossina; 
Distribution and habits of tsetse flies; Their relationship to trypanosomiasis; 
Investigations by Bruce and others; Tsetse fly control; Characteristics of 
the family Hippoboscidse; The "sheep tick" or "louse fly;" Its effect; 
Treatment. 

CHAPTER \l 

The Dipterous Laev.e • 50 

Myasis; The "screw worm fly;" Its habits; Effect of its attack; Pro- 
tective measures; Treatment; The flesh flies; The blowfly; Its habits; 
Protective measures; Characteristics of the familj' Oilstridue; The horse 
bot flies; Gastrophilus mleslinalis; Its habits and life history; Effect of the 
fly and lai'vae upon horses; The red-tailed bot-fly; Its habits and effect; The 
chin fly; The ox bot or warble flies; Their life history; Their economic im- 
portance; The sheep bot fly; Its habits and life history; Effect of the at- 
tack of the fly and its larva:'; Protection and treatment. 

CHAPTER VII 

The Fle.^s 65 

CharacterLstics of the order Siphonaptera; The dog, cat, and human fleas; 
Differentiation of species; Life history; Relation of fleas to the transmis- 
sion of infectious diseases; Treatment and control. 

CHAPTER Vni 

The Lice 70 

The sucking lice; Characteristics of the order Siphunculata; The biting 
lice; Characteristics of the order Mallophaga; Pediculosis of domestic ani- 



CONTENTS ix 

PAGE 

mals in general; Pediculosis of the horse; Pediculosis of cattle; Pediculosis 
of the sheep and goat; Pediculosis of the hog; Pediculosis of the dog and 
cat; Pediculosis of man; Control and treatment of pediculosis. 

CHAPTER IX 

Lice of Poultry; The Bedbug . 82 

Prevalence and effect of poultry lice; Species infesting chickens; Species 
infesting turkeys; Species infesting ducks and geese; Species infesting 
swan; Species infesting pigeons; Control and treatment of poultry lice; 
Characteristics of the order Hemiptera; Characteristics of the family Cimi- 
cida;; The common bedbug; Its habits and effect of its bite; The bedbug as 
a pest of poultry; Control. 

CHAPTER X 

The Mites 94 

Characteristics of the class Arachnida; Characteristics of the order Acar- 
ina; Parasitism of the Acarina; Acariasis; Characteristics of the famil}' Ga- 
masidse; The gamasid mites of poultry; Habits and effect of their attack; 
Control; Characteristics of the family Trombidiidse ; The harvest mites, 
chiggers, or red bugs; Habits and effect of their attack; Treatment; The 
mange, scab, or itch mites; Characteristics of the family Sarcoptidse; The 
genera Sarcoptes; Notoedi-es, Otodectes, Cnemidocoptes, Laminosioptes, 
Cytoleichus, Psoroptes, and Chorioptes; Their respective characteristics, 
hosts, and modes of attack; Characteristics of the family Demodecidse; 
Mange and scabies of the various domestic animals; Sarcoptic mange; De- 
modectic or foUicular mange; Notoedric or head mange of the cat and rab- 
bit; Otodectic or auricular mange; Psoroptic scabies; Auricular scabies of 
the rabbit; Chorioptio or leg scabies; Symptoms, development, lesions, diag- 
nosis, and transmission of mange and scabies. 

CHAPTER XI 

Treatment of M.^nge and Scabies 120 

General considerations; Treatment of sarcoiJtic mange of the horse; Of 
the dog; Of the goat; Of the sheep; Of cattle; Treatment of notoedric mange 
of the cat and rabbit; Treatment of demodectic mange; Treatment of oto- 
dectic mange; Treatment of psoroptic scabies of the sheep; of cattle; Of 
the horse; Of the rabbit. Treatment of chorioptic scabies of the horse; Of 
cattle. 

CHAPTER XII 

Mange of Poultry 132 

The burrowing mite of poultry; Leg mange or "scaly leg"; Its course 
and treatment; The dej^luming mite; The deep-seated acariases of birds; The 
family Cytoleichidse; The connective tissue mite; The air passage mite. 



X CONTENTS 

CHAPTER XIII 

PAGE 

The Ticks 136 

Structure of ticks in general; rharacteristios of the superfamily Ixo- 
doidea; Characteristics of the family Argasidoe; The fowl tick; Its habits and 
effect upon the host; Control; The spinose ear tick; Its habits and effect upon 
the host; Treatment; Cliaracteristics of the family Ixodidae; Description of 
genera; Species found upon domestic animals in the United States; The 
Texas-fever or Southern cattle tick; Biological data established by the Zool- 
ogical Division of the United States Bureau of Animal Industry; Life his- 
tory of the Texas-fever tick; Its nonparasitic development; Its parasitic 
development; Loss occasioned by the Texas-fever tick; Progress made in its 
eradication; The order Linguatulida; Linguntula rhinaria of the nasal cavi- 
ties of mammals. 



PART II 
THE INTERNAL PARASITES 
CHAPTER XIV 

PHYLfM II. Pl.^tyhelminthes; The Flokes and Tapeworms 155 

Classification of the parasitic worms; Characteristics of the Platyhelm- 
inthes; Characteristics of the class Trematoda; The liver flukes; Their life 
history; Prevalence of fascioliasis; Infection; Migration of flukes within the 
dpfinitivp host and pathogenesis; Fa-scioUasis of the sheep; Fascioliasis of 
cattle; Control and treatment; The blood fluke; Bilharziosis; Characteristics 
of the class Cestoda; Characteristics of the family Taeniidie; Life history of 
tapeworms; Their parasitism. 

CHAPTER XV 

T^NiASis 174 

General consideration of the effect of tapewonns upon their hosts; Tape- 
worms of the horse; Tapewonns of cattle, sheep, and goats; Tapeworms of 
the dog; Dog tapeworms in relation to human infection: Tapeworms of 
the cat; Tapeworms of the rabbit; Characteristics of the family Diphyllo- 
bothriid;e; Occurrence of species; Treatment of ta?niasis of the dog; Pre- 
vention; Treatment of tseniasis of the cat; Treatment of taeniasis of sheep, 
goats, and cattle; Treatment of tteniasis of the horse. 

CHAPTER XVI 

Tapeworms of Chickens 189 

Characteristics of species; Investigations as to their relative occurrence; 
Symptoms; Control; Treatment. 



CONTENTS xi 

CHAPTER XVII 

PAGE 

The Tapeworm Larv^ 194 

Pathologic importance," Forms and their characteristics, Cysticercosis 
or measles; Beef measles; Its occurrence; Degeneration and vitality of the 
cysts; Pork measles, Its occurrence; Degeneration and vitality of the cysts; 
Measles of the sheep; Coenurosis or gid; Its occurrence; Its development; 
Its post-mortem appearance; Its symptoms; Control and treatment; Echin- 
ococcosis or hydatid disease; Structure of the echinococcus cyst; Its de- 
velopment; Post-mortem appearance in echinococcosis; Symptoms; Con- 
trol. 

CHAPTER XVIII 

Phylum III. Coelhelminthbs; The Smooth and Segmented Roundworms ... 216 
Characteristics of the Ccelhelminthes; Characteristics of the class Ne- 
mathelminthes; Characteristics of the order Nematoda: Parasitism of the 
nematode worms in general; General considerations as to treatment. 

CHAPTER XIX 

Nematoda; Family I. Ascarid^; The Large Roundworms of the Intestine 229 
Characteristics of the Ascaridje; Investigations as to life history; Ascar- 
iasis; Ascarids of the horse; Occurrence of equine ascariasis; Its etiology, 
control, and treatment; Characteristics of the family Oxjairidse; Oxyuriasis 
of equines; Ascarids of the dog and cat; Ascarids of the hog and sheep; As- 
carids of the ox; The family Heterakidse and heterakiasis of poultry. 

CHAPTER XX 

Nematoda; Family IV. Filariid^.; The Thbead-like Worms 244 

Characteristics of the Filariidae; Parasitism; Filaria of the horse; Their oc- 
currence; Effect of filariasis upon equines; Filaria of sheep and cattle; Filaria 
of the dog; Hematic filariasis; Filaria of the hog; Filaria of poultry. 

CHAPTER XXI 

Nematoda; Family V. Strongylid^; Subfamily I. Metastrongylin^ 

Worms of the Respiratory Tract 255 

Characteristics of the Strongj'lidae ; Parasitism; Strongylosis; Characteris- 
tics of the-Metastrongylina; Parasitism; Bronchial and pulmonary strongy- 
losis of the sheep and goat; Its symptoms, course, and prognosis; Bronchial 
and pulmonarj' strongylosis of cattle; Its symptoms, course, and prog- 
nosis; Bronchial and pulmonary strongylosis of the pig; Its occurence and 
symptoms; Bronchial and pulmonary strongylosis of the horse; Cai'dio- 
pulmonary strongylosis of the dog; Pulmonary strongj-losis of the cat; Post- 
mortem appearance in bronchial and pulmonary strongylosis; Develop- 
ment, etiology, control, and treatment of bronchial and pulmonnry strongy- 
losis. 



xii CONTENTS 

CHAPTER XXII 

PAGE 

Nematoda; Subfamily II. Trichostrongylin.e; Worms of the Stomach 

AND Intestine 268 

Characteristics of the Trichostrongylime; Parasitism; Gastro-intestinal 
strongylosis of the sheep and goat; Its occurrence; Its symptoms; Gastro- 
intestinal strongylosis of cattle; Its occurrence; Its symptoms; Post-mortem 
appearance in gastro-intestinal strongylosis, Development, etiology, con- 
trol, and treatment of gastro-intestinal strongylosis. 



CHAPTER XXIII 

Nematoda; Subfa.mily III. Sthongylin.e; Worms of the Large and Small 

Intestines; Other Strongyles 280 

Characteristics of the Strongylinse; Parasitism; Nodular strongylosis of 
the sheep and goat; Its occurrence; Its development; Its post-mortem ap- 
pearance; Its sjonptonis; Treatment; Nodular strongylosis of cattle; Nodu- 
lar St rongj-losis of the hog; Strongylosis of the large intestine of the sheep and 
goat; Strongylosis of the intestines of the horse; Its development; Its symp- 
toms; Its post-mortem appearance; Intestinal strongylosis of the dog and 
eat; Oth(M' Strongylina>; Tracheal strongylosis of chickens; The kidney 
wonn of the hog; Family Eustrongylida; and eustrongylosis. 



CHAPTER XXIV 

Nematoda; Family VII. Trichinellid.b 299 

Characteristics of the Trichinelhdse; The "whip-worms'' of the large 
intestine; TrichincUa spiralis and trichinosis; Life history of Trichinella 
sjiiralis; Intestinal trichinosis; Muscular trichinosis; Degeneration of the 
trichina cyst; Infection; Sj-mptoms of intestinal and muscular trichinosis in 
hogs; Trichinosis in rats and mice; Prophj'laxis. 

CHAPTER XXV 

The Thorn-he.^ded Worm; The Leeches 306 

Characteristics of the order Acanthocephala; The thorn-headed wonn of 
the intestines of the hog; Its Ufe history; Its occurrence; Its pathogenicity; 
Symptoms produced; Treatment; Characteristics of the class Annelida; 
Characteristics of the order Hinidinea; The horse leech; The medicinal 
leech; Sources of infestation by leeches; Their effect upon the animal at- 
tacked; Treatment. 



CONTENTS xiii 

PART III 

THE PATHOGENIC PROTOZOA 
CHAPTER XXVI 

PAGE 

Phylum IV. Protozoa ! 311 

General consideration of the Protozoa; Characters differentiating Pro- 
tozoa from Metazoa; Ameba, its main features for study; Parasitism of 
the Protozoa; Progress of research; Relationship of -arthropods to infection 
with protozoal diseases; Evolution of pathogenicity in Protozoa; Methods 
of reproduction in free and parasitic forms; Life history of the malaria or- 
ganisms; The schizogonic or asexual cycle; The sporogonic or sexual cycle; 
Classification of pathogenic species. 

CHAPTER XXVII 

The Protozoan Subghoups; Diseases Due to Protozoa 324 

Characteristics of the class Rhizopoda; Infectious entero-hepatitis of tur- 
keys; Amebic dysentery of man; Characteristics of the class FlageUata; 
Characteristics of the order Spirochetida; Spirochetosis of poultry; Char- 
acteristics of the order Trypanosomatida; Parasitism; Transmission of 
the infecting organisms; Nagana or "fly disease;" Surra, Mai de Caderas; 
Dourine; Try-panosovia mnericanum; Characteristics of the class Sporozoa; 
Characteristics of the order Coccidia; Coccidiosis; Eimeria stiedos; Cocci- 
diosisof rabbits; Diplospora bigemina; Coccidiosis ot dogs; Coccidium zurni; 
Red dysentery of cattle; Eimeria aviwn; Coccidial enteritis of chicks; Char- 
acteristics of the order Hemosporidia; Piroplasma bigeminum; Texas-fever 
of cattle; Its occurrence; Exposure and development; Its sjinptoms; The 
acute type; The chronic type; Prevention and treatment; Characteristics of 
the order Sarcosporidia; Sarcosporidiosis; Mode of infection. 

Glossary 353 

Index 359 



LIST OF ILLUSTRATIONS 

PIG. PAGE 

1. Diagram of an insect 16 

2. Diagram of internal parts of an insect 16 

3. Diagram of insect's heart 17 

4. Mouth parts of a biting insect 17 

5. Diagram showing tracheal system of an insect IS 

6. Abdomen of locust, showing spiracles IS 

7. Head of bee, showing compound eyes, ocelli, and antennse 19 

8. Metamorphosis of the house Hy 19 

9. Diagram of segments of arthropod, sho'W'ing leg muscles, etc 19 

10. Eggs and larvae, of Culex mosquito 24 

11. Pupa, of Culex and Anopheles mosquitoes 26 

12. Culex pungens, male and female 27 

13. Anopheles quadrimaculatus, male and female 28 

14. Position of Anopheles and Cules at rest 2S 

15. Breathing position of larva, of Anopheles and Culex 29 

16. Eggs of Anopheles 30 

17. The Southern buffalo gnat 32 

18. Larva of Southern buffalo gnat 33 

19. Pupa of Southern buffalo gnat 33 

20. The black horsefly 36 

21. The green-head fly 36 

22. The stable or stinging fly 39 

23. The horn fly 42 

24. Tsetse fly .- 44 

25. The "sheep tick." 47 

26. The screw worm fiy 51 

27. Metamorphosis of the flesh fly 52 

28. Horse botfl}-, showng eggs, larva, and adult 54 

29. Ox botfly, Hypodemia lineata 58 

30. Ox botfl)', Hypoderma bo^'is 59 

31. Eggs of Hj'podenna lineata 59 

32. Larval stages of Hypodenna lineata 61 

33. The sheep botfly, showing larva, pupa, and adult 63 

34. The dog flea, anterior portion of body 66 

35. The human flea, anterior portion of body 66 

36. The dog flea, sliowing development and mouth-parts 67 

37. Larva of flea 68 

38. Sucking louse of liorse, Hcematopinus asini 73 



xvi LIST OF ILLUSTRATIONS 

FIG. PAGE 

39. Biting louse of horse, Trichodectes paruinpilosus 73 

40. Suclving louse of cattle, Haematopiiius eurysternu.s 74 

41. .Suclcing louse of calves, Linognatlius (Ha?matopinus) vituli 75 

42. Biting louse of cattle, Trichodectes scalaris 75 

43. Sucking louse of sheep, Linognathus (Hsematopinus) pedalis 76 

44. Biting louse of sheep, Trichodectes spha>rocephalus 77 

45. Sucking louse of hog, Hsematopinus suis 78 

46. Sucking louse of dog, Linognathus (Ha>matopinus) piliferus 78 

47. Biting louse of dog, Trichodectes latus 79 

48. Louse of the cat, Trichodectes subrostratus 79 

49. Louse of chicken, Goniocotes gigas (G. abdominalis) 83 

50. Louse of chicken, Lipeurus caponis (L. variabilis) 83 

5L Louse of chicken, Menopum trigonocephalum (Menopon pallidum). 83 

52. Louse of turkey, Goniodes stylifer 85 

53. Louse of turkey, Lipeurus meleagridis (L. polytrapezius) 85 

54. Louse of turkey, Menopum (Menopon) biseriatum 85 

55. Louse of duck, Lipeuris anatis (L. squalidus) 85 

56. Louse of ducks and geese, Trinotum (Trinoton) hn'idum 87 

57. Louse of swan, Philopterus (Docophorus) cygni 87 

58. Louse of swan, Ornithonomus (Ornithobius) cygni 87 

59. Louse of pigeon, Goniocotes conipar 87 

60. Louse of pigeon, Goniodes damicornis 87 

61. Bedl)ug, adult female, mouth-parts etc 91 

62. Diagram of the anatomj' of a spider 95 

63. Gamasid poultry mite, young and adult 98 

64. Mange mite of horse 104 

(35. Mange mite burrow in human skin 105 

66. Colts affected vnih sarcoptic mange 106 

67. Leg scab mite of horse 109 

68. Scab mite of sheep, female . Ill 

69. Seal) mite of sheep, male Ill 

70. Follicular mange mite 116 

71 . Mange mite of cat and rabl)it 118 

72. Auricular scab mite of rabbit 118 

73. Portable dijjinng vat for sheep 127 

74. Mite of scaly leg of poultry, male and female 133 

75. Foot of fowl affected with scaly leg 134 

76. Capitulum of tick 137 

77. Capitulum, scutvmi, and fore leg of Texas fever tick 137 

78. Stigmal plates of ticks Margaropus, Ixodes, and Dei-macentor . . . . 138 
78a.' Photomicrograph of stigmal plate of Texas fever tick 138 

79. Fowl tick, adult and larva 139 

SO. Spinose ear tick, mTnphal foi-m 141 



LIST OF ILLrSTRATIOXS x\ii 

FIG. PAGE 

81. The castor-beau tick 143 

82. The American dog or Avood ticlv 144 

83. Linguatula rhinaria 153 

84. Planarian worm 1.56 

85. Liver fluke, Fasciola hepatica 157 

86. Reproductive organs of liver fluke 158 

87. Fasciola hepatica, F. americanus, Dicroccelium lanceatum 161 

88. Life history of liver fluke 162 

89. Blood fluke, male and female 168 

90. Segment of Tsenia saginata, sho'ndng sexual organs 171 

91. Tapeworms of the horses 175 

92. Tapeworm of cattle and sheep, Moniezia expansa 176 

93. Fringed tapeworm of sheep, anterior segments 177 

94. Tapeworm of dog, Dipyhdium caninum ISO 

95. Rostellum of JDipylidium caninum ISO 

96. Egg packet and Cysticercoid of Dipyhdium caninum 180 

97. Tapeworm of dog; Tsenia hydatigena ISO 

98. Tapeworm of dog. Taenia pisiformis 180 

99. Tapeworm of dog, Echinocoecus granulosus 180 

100. Rostellum of tapeworm of cat. Taenia taemaefomiis 184 

101. Diphyllobothrium latum 186 

102. Tapeworm of chicken, Choanotania infundibulifoiTnis 189 

103. Scolex of ChoanotEenia infundibuliformis 190 

104. Scolex of Davainea tetragona of cliicken 190 

105. Scolex of Davainea echinobothrida of chicken 190 

106. Tapeworm of man. Taenia saginata 196 

107. Diagram of Cysticercus 198 

108. Fragment of beef muscle, showing cysts of Cysticerus bovis 19S 

109. Scoleces of Taenia solium, T. saginata, and Diphyllobothrium latum . . . 199 

110. Eggs of Taenia saginata and T. solium 200 

111. Alature segments of Tfenia saginata and T. solium 200 

112. Stages in tapeworm development 201 

113. Portions of adult gid tapewomi, jMulticeps multiceps 205 

114. Diagrammatic section of Multiceps (CcEUurus) cyst 206 

115. Brain of lamb, sho'ning furrows produced by young gid bladder«-onn. . 206 

116. Gid bladdenvo.nn, showing immature tapewonn heads 206 

117. Diagram of Echinocoecus hydatid 211 

118. Echinocoecus granulosus, sho^nng hydatid with brood capsules 214 

119. Transection of Ascaris equi 217 

120. Posterior extremity of male nematode wonn 21S 

121. Cephalic extremity of an ascarid wonn 229 

122. O.xyuris equi 236 

123. Belascarismarginata, showing head and male and female 23S 



xviii LIST OF ILLUSTRATIONS 

FIG. PAGE 

124. Egg of Ascaris lumbricoides 240 

125. Ascaris lumbricoides, male and female 240 

126. Heterakis perspicillum, male and female, and H. vesiculaiis of poultry. 242 

127. Setaria lahiato-papillosa, male and female 245 

128. Gongylonema scutata, anterior and posterior views 247 

129. Dirofilaria immitis, male and female 249 

130. Lung wonn of sheep and goat, Dictyocaulus filaria, male, female, and 

eggs 257 

131. Lung wonn of sheep, goat, and rabbit, Synthetocaulus rufe.scens, male 

and female 257 

132. Lung wonn of cattle, Dictyocaulus ^'iviparous 259 

133. Lung wonn of ))ig, Metastrongylusapri, male and female 260 

134. Stomach wonn of sheep, goat, and cattle, llffmonchus contortus, 

female 269 

135. Ha>monchus contortus, anterior portion of body • 269 

136. Ha-monchus contortus, enlarged posterior extremity of male 269 

137. Cooperia curticei, male and female 270 

138. Cooperia curticei, enlarged anterior portion 270 

139. Ostertagia marshalli, male and female 270 

140. Trichostrong.ylus instabilis, male and female 271 

141. Ostertagia o.stertagi, male and female 273 

142. Ostertagia ostertagi, jjosterior extremity of male enlarge(l 273 

143. Ncmatodirus filicollis, male and female and enlarged anterior portion . . 274 

144. Cooperia onco{)hora, male and female 274 

145. Qilsophagostomum columbianimi, male and female 282 

146. CEsojihagostomum cohunlnanum, enlarged anterior liortion 282 

147. (Esophagostomum columliianmn, enlarged bursa of male 283 

148. (Esophagostomum \enulosum, male and female 283 

149. ffi.sophagostomimi venulosum, enlarged anterior portion 283 

1.50. ffisophago.stomum venulosum, enlarged bursa of male 283 

151. (Esophagostomum radiatum, male and female 286 

152. (Esoj)liagostomum radiatum, enlarged anterior portion 286 

153. (Esojihagostoimun radiatum, enlarged bursa of male 286 

154. Chabertia ovina, male and female 287 

155. Strongylus equinus, male and female 288 

156. Hook-wonii of dog and cat, Ankylostoma canina, male and female. , 292 

157. Bunostomum jjhlcbotomum, male and female 293 

158. Tracheal wonn of poultrj'^, Syngamus trachealis, male and female . 294 

159. Dioctophj-me renale, male 297 

160. Trichuris ovis, male and female 300 

161. Trichuris ovis, egg 300 

162. Trichinella spiralis, male and female 301 

163. Trichinella sjiiralis, encysted lan-a in mu.scle 302 



LIST OF ILLUSTRATIONS xix 

FIG. PAGE 

164. Trichinella spiralis, microphotograph of cyst 304 

165. The thorn-headed wonn, Gigantorhynchus hirudinaceus 307 

166. Cephalic extremity of thorn-headed womi 307 

167. The horse leech 308 

168. Ameba proteus 312 

169. Spirocheta pallida 327 

170. Hen suffering from acute spirochetosis 328 

171. Piroplasma bigeminum 348 

172. Foniis of Sarcosporidia, shown in infected muscle 351 

Plates. Page 

I. Texas fever tick, male and female, with details 146 

II. Texas fever tick, stages of engorgement and details 147 

III. Evolution of the parasite of kala-azar 317 

IV. Life cj^cle of the malaria parasite 321 

y. Various species of Tr3'panosoma 331 

VI. Percheron stallion before and after development of dourine 338 

VII. Percheron mares, showing chronic dourine and last stage 340 

VIII. Coccidian life cycle 344 

TABLES 

Classification of parasites of the clas.s Insecta 20 

Life history of horse botfly, Gastrophilus equi 55 

Life history of sheep botfly, (Estrus ovis 63 

Classification of parasites of the class Arachnida 96 

Summary on nonparasitic periods in development of Texas fever tick 149 

Summary on parasitic periods in de-velopment of Texas fever tick 150 

Life histories of dog tick and Texas fever tick compared 151 

Classification of parasites of the phylum Platyhelminthes 157 

Life history of liver fluke, Fasciola hepatica 163 

Life history of beef tapewonn, Tsenia saginata 172 

The principal tapewomis, with their larvae and hosts 173 

Synopsis of tapeworm larvee 194 

Life history of tie gid tapewonn, Multiceps multiceps 207 

Life historji- of Echinococcus granulosus 213 

Classification of parasites of the phylum Ccelhelminthes 222 

Life history of Trichinella spiralis 303 

Classification of parasites of the ijhyluni Protozoa 322 



PARASITES AND PARASITOSIS OF THE 
DOMESTIC ANIMALS 



PARASITES AND PARASITOSIS OF THE 
DOMESTIC ANIMALS 

PART I 

PRELIMINARY CHAPTERS 

THE EXTERNAL PARASITES 

CHAPTER I 
INTRODUCTION 

The earth's vast laboratory of living matter includes a flora and fauna 
in which all of the highly diversified forms encounter conditions operating 
to restrict their multiplication and to govern the predominance of cer- 
tain forms over others. These conditions are constituted, first, by 
topographic and climatic variations rendering certain localities more or 
less inhospitable to some organisms, while others ma3^ be uninfluenced or 
perhaps benefited. Second, there is the behavior of living things toward 
one another; this may be relatively harmonious or there may be an 
intense rivalry in which organisms encroach or prey one upon the other, 
the least fit for the strife being driven to less favorable habitats, progres- 
sively dwarfed, or ultimately becoming extinct. Though most of these 
inhibitive influences are not apparent to cursory observation, they are, 
nevertheless, numerous and varied as well as constant in their operation, 
constituting a prime factor in the evolution and specialization of organic 
forms. 

There is, then, a perpetual struggle for existence, which may lead to 
the seeking of shelter from the conflict in a changed and often degenerate 
mode of life to which the organism becomes adaptivelj^ modified. Thus, 
through such influences, a terrestrial animal maj' be driven to an ar- 
boreal, or even an aquatic or semiaquatic, existence. A defenseless little 
member of the Insectivora burrows and becomes subterranean, while 
another finds protection in the nocturnal habit; others seek the shelter 
of caves or rock crevices, and we often find creatures, usually somewhat 
degenerate, in places which seem to us quite unfavorable to their suis- 
port. While in such cases the animal continues to lead a free and in- 



2. PARASITES OF THE DOMESTIC ANI]MALS 

dependent, often solitary existence, on the othei- hand, a communion of 
Hfe's interests may he estahlished between two organisms which, it is 
surmised, is foimded upon some mutual advantage in the strife. To 
such association the general tenn symbiosis has been applied and each 
of the organisms concerned is referred to as a symljiont. Though there 
is by no means a uniformity in the application of terms referring to the 
symbiotic relationship, a usage is adopted here that seems best defined, 
and by which symbiosis is sul)divided into the three categories, (1) mu- 
tualism, (2) commensalism, and (3) parasitism. In the first there is a 
reciprocal advantage derived from the imion: in the second but one 
sTOibiont is benefited though the other suffers no harm, while in the 
third division one receives an advantage to the detriment of the animal 
or plant which it invades. There is, however, no sharp line of demarca- 
tion between these three states of living together, and it may be difficult 
to determine in some ca.ses whether one or both symbionts receives 
lienefit from the union, or whether one is or is not injured by it. 

One of the more obvious examples of mutualism is the case of the 
hermit crab and the sea anemone. This cral) selects a shell, as that of 
the whelk, foi' its halsitation, from the opening of which it projects only 
its head and claws. On the svu'face of the shell may often be found a sea 
anemon(> fastened near the opening with its mouth and tentacles in the 
vicinity of the crab's head. The anemone in this position not only in a 
measure serv(>s to conceal the hermit crab from its enemies, but the 
creatiu'e that would jiicy vipon the crab must first reckon with the 
dangerous stinging threads with which the tentacles of the anemone are 
armed. The anemone, in its tm-n, is benefited by being carried about 
by the crab and aided in this way in obtaining its food. 

Such associations are not always of mutual advantage, and may be 
more in the nature of an invasion of one animal upon or within the 
body of another, the invading animal alone deriving benefit, while the 
animal upon which the association is forced, though not benefitmg, 
may in no way suffer from it. A familiar foim of this living together 
(commensalism) is the little ci-ab so conmionly found in the shell of the 
oyster. The oyster is not harmed by its pi-esence, but the crab is bene- 
fited by the protection which the shell affoids. Another more curious 
example of such association is afforded among the vertebrates by the 
species of Remoia, or suck fishes, which have the first dorsal fin modified 
into a sucking disk on top of the head. By means of this disk it attaches 
itself to a shark or other large fish, and is thus carried about, detaching 
itself only to secure food. Its benefit from such association is in being 
carried to new feeding gi'ounds without effort of its own, and in the 
shelter from its enemies which the body of the larger fish may afford. 
The host, on the other hand, cannot be benefited, nor does it seem to 
suffer by the iDresence of its uninvited guest. 



INTRODUCTION 3 

Whether this relationship between different species is of reciprocal 
advantage or of benefit to but one, neither of the symbionts lives upon 
or at the expense of its co-symbiont, and neither has entirely renounced 
its independence. In true parasitism the invading animal lives upon the 
tissues of its host, deprives it of a portion of its nourishment; or is in 
other ways injurious to it. There are many examples of this form of 
symbiosis, and students of animal life are famihar with the conditions 
that seem always to attend it, such as the degenerative and adaptive 
modifications occurring in the parasite. 

It is the common habit of many animals, however, to prey upon the 
bodies of other animals, and we should distinguish, so far as we may, 
between those which are predatory and those which are parasitic. The 
former are free and exercise their powers of sense and cunning in snaring 
or chasing their prey, while the latter, in fully acquired parasitism, live 
on or in the bodies of their victims, often burrowing into and consummg 
the body tissues, leading a lazy, beggarly existence in which all of the 
faculties of special sense and prowess, so highly developed in predatory 
animals, become degenerate and atrophied. 

Parasitism is found throughout the range of animal life from the 
unicellular to the vertebrate, and, though a sharp distinction between 
predaceous and parasitic animals may not be made, in view of the de- 
grading influence of the parasitic habit, the difference between the 
simplicity of degeneration and the simplicity of primitiveness should be 
clearly defined. In the development of a primitively simple aninial the 
young stages are more simple than in the adult and it has only simple 
ancestors. In the degenerate animal, on the other hand, the ancestors are 
often more complex and the young stages are of a higher grade than the 
stage of the adult. The adoption of any mode of life which withdraws 
from the activities necessary to survival in a free existence seems to 
bring about this condition of degradation. Of this we have a remarkable 
example outside of the realm of parasitism in the Tunicata. These 
aberrant animals, in the stage of the free-swimming larva, have a chordal 
axis which in nearly all of the different species becomes entirely lost 
before they reach maturity. After passing the "tadpole" stage there 
follows an extreme specialization to the fixed habit which most tunicates 
retain throughout their adult life, becoming what are commonly known 
as sea squirts, mere attached, plant-like sacs, emitting a jet of. water 
when disturbed, and from which all chordate features have been entirely 
lost. 

The degenerative changes which a parasite undei-goes concern mostly 
the nervous system, the organs of locomotion, and those of nutrition, the 
nervous system becoming reduced to the most indispensaljle portion, 
while of the sense-organs nothing may be left except those of touch. The 
locomotor apparatus may Ijecomo modified into claws or hooks for 



4 PARASITES OF THE DOMESTIC ANIIMALS 

clasping the hairs of the host, or it may ahnost if not completely dis- 
appear and be replaced bj' such organs of fixation as sucking-disks. As 
the contents of the alimentarj' canal or tissue fluids of the host upon 
which the verminous parasite is nourished need scarcely any digestion, 
the digestive organs become simplified or may be quite lost, the absorb- 
tion of nutriment in the latter case taking place entirely through the 
body integument, as in some of the worms which infest the intestines of 
man and other animals. The degi'ee of decadence will depend upon the 
degree of dependence upon the host. In this latter respect the parasitism 
maj' be ojjtional, as in the case of the mosquito, which may live upon the 
juices of plants but prefers a meal of warm blood, or it may be obhgate, 
depending upon another for its means of subsistence, though such 
obligate parasites as the biting flies, fleas, and bedbugs may also live 
free and only occasionly visit their hosts, a form of parasitism which 
mav be accompanied bv little modification of the adaptabiUty to a free 

me. 

In the event of the i)arasite becoming progressively degraded into one 
which not onh' seeks its host for food, Init has become dependent upon 
it for both its nutrition and place of abode, all of the above mentioned 
phenomena of adaptation become more conspicuous. There is furnished 
a very good example of such a transformation in the sheep tick {Melo- 
phagus ovinus), not a true tick, however, but a fly which, originally an 
occasional visitor, has, like the louse, taken permanent abode upon its 
host. No longer taking the aerial flight of its discarded free life, this 
fly has become wingless, and, furthermore, is enabled to pass its entire 
life cj'cle upon the body of the host animal by a remarkable method of 
reproduction involving the retention of the eggs in the oviducts until 
development has passed through the larval stage. It is not until readj- to 
pass into the stage of the pupa that the larvae are extruded, the pupal 
case then being attached to the individual wool fibers. From this case 
the young insect, on becoming sufficiently developed, makes its escape 
and proceeds to feed and grow, thus rounding out a complete parasitic 
cj'cle. 

While the easy life of the parasite tends to degeneration, the perpetua- 
tion of the species becomes more precarious, and the organs of reproduc- 
tion undergo a marked development. If a host animal dies most of its 
parasites, especially those existing in the interior of its body, die with 
it, and, were it not that the eggs find lodgment in a new host, the parasitic 
species would in a short time become extinct. The transmission of but 
few of these eggs is successfully accomplished, and in compensation they 
must be produced in enormous numbers, well protected from the manj' 
elements of destruction which they encounter. The mode of reproduc- 
tion is one of the principal factors determining the conditions of par- 
asitism, and, while the above modifications pertain more to those 



INTRODUCTION 5 

dwelling continuously upon or within the bodies of their hosts, we have 
in the (Estridse, among the dipterous insects, a cycle involving internal 
parasitism during the larval stage, a familiar example being the common 
horse botfly (Gastrophilus intestinalis) , the development of which is 
given on page 54. It is plain that a very small percentage of the eggs 
deposited by this fly can reach the horse's mouth, and that, having got 
thus far, many of the larvae must be destroyed or pass entirelj' through 
the intestinal tract without having succeeded in becoming fixed to the 
mucous membrane. For this there seems to be compensation in the 
large number of eggs deposited by the persistent female. 

Wliile in some cases the complete life cycle of a parasite requires but 
one host, often, for reasons stated in the foregoing, two successive and 
generally specifically different hosts are required. A rather compH- 
cated example of the latter case is the life history of the comnaon liver 
fluke {Fasciola hepatica), one of the flat worms infestmg in its adult 
state the livers of Herbivora. It will be noted in referring to the cycle of 
this parasite, given in detail elsewhere (page 160), that it is a veiy 
hazardous one, and that its completion must depend upon the co- 
operation of numerous favorable conditions. The eggs, of which each 
individual fluke is capable of producing iia the neighborhood of one 
hundred thousand, must reach the exterior amid surroundings favorable 
to their hatching. If hatched, the larva must escape its many aquatic 
enemies and within a few hours find a suitable snail host. Pro\ading the 
snail is not eaten by a duck, or does not otherwise perish during this 
phase of the cycle, it issues from its host as the free-swimming cercaria, 
when it is again liable to fall prey to various small aquatic animals. 
Escaping this and becoming encysted, the chance of any herbivorous 
animal coming along and swallowing it is very small. The relation of 
the enormous number of eggs, and the number of individuals which one 
egg may produce, to the survival of the species amid conditions fraught 
with such dangers seems quite evident. 

In general it may be sard as to the propagation of parasites that their 
prodigious fecundity and the great \'ital resistance with which most of 
them are endowed enables species to survive and perpetuate their kind 
amid varied destroying influences which otherwise would brmg about 
their extermination. The tapeworms inhabiting the intestines of man 
and other animals, afford another example of extreme parasitism accom- 
panied by this remarkable development of the reproductive function. 
Here is a creature so altered to its degenerate existence that it has be- 
come devoid of mouth and mtestine, the body consistmg of a scolex, 
usually referred to as the head, from which are give oft" segments which 
remain imited until there is formed, as in Tcenia saginata of man, a 
band-shaped colony of from twelve hundred to thirteen hundred or 
more, passing back from the worm's attachment to a length which may 



6 PARASITES OF THE DOMESTIC ANIMALS 

exceed twenty feet. After about the six huiulredth, each segment is a 
mature and sexually complete individual, which later, as it is pushed on 
by new segments formed at the head, becomes filled with fecundated 
eggs. By the sviccessive detachment of these "ripe" segments and their 
passage from the body of the host, it has been estimated that Tosnia 
saginata might throw off in a year as many as one hundred and fifty 
million eggs, of which but an infinitesimal number, as is quite evident, 
will reach the body of their proper bovine host for larval development. 
Again, having been so fortmiate, it is improbable that the larviB will, 
while living, reach the intestines of the hmnan host necessary for their 
further development into adult worms. 

Here, then, is an animal well showing the degree of degeneration 
which may be reached in extreme parasitism; there are no organs of 
locomotion, no organs of special sense, no organs of digestion, no organs 
of respiration, and none of true circulation. The body consists of a long 
band of connected segments, each, when mature, bisexually complete 
and in itself a sort of independent reproductive individual, the entire 
energy of the organism concentrated upon the function of reproduction 
that the perpetuation of the species may he insured amid the perils with 
which this process is beset. 

In many forms permanently parasitic there is an early period of 
development in which organs of locomotion are distinctly present, but, 
as the animal matures, these fail to develop or become lost. If it is 
assumed that this gradual loss of organs, change of structure, and protec- 
tive transmission of the embryo to an intermediate host is due to the 
parasitic- life, it seems reasonable to conclude that all of the parasitic 
groups have been derived from free-living forms, and that, as parasitism 
became a more fixed habit, such structural changes were in the course of 
time brought about as would make this mode of life obligatory. A re- 
view of the observed facts, then, in their biologic relationship, leads to 
the conclusion that .s>inbiosis, of which parasitism is a form, has its 
causative basis in the struggle for existence, the s^anbiotic association in 
more or less measure mitigating the hazards to one or both symbionts. 
It further follows that, though some forms have undergone an extreme 
modification, through related contemporary free-living types, their true 
systematic i)osition may be estaljli.shed. 



CHAPTER II 

FORMS OF PARASITISM AND INFLUENCE UPON THE HOST 

Forms of Parasitism 

The student of parasitology will be greatly aided by an orderly and . 
progressive pursuit of the subject, an elementary requisite to which is a 
broad conception of what is implied by the various tenns used in the 
chapters which are to follow. Those below are not given with the recom- 
mendation that they be memorized as to the exact wording set forth in 
their definitions; more essential is such an understanding that examples 
can readily be picked out, a typical illustration always being in mind for 
application to the term at hand. With such a conception the student 
should be able to formulate his own definitions, and this will be of more 
advantage to him than accepting those set forth according to the con- 
ceptions of another. 

Though some of the following terms have been treated of in foregoing 
introductory remarks, they are here included for more concise definition 
and to make the list inclusive. 

Symbiosis is the more or less pennanent living together of two plants, 
two animals, or an animal and a plant, the union being in a measure 
beneficial to both, or to one with or without hann to the other. 

Symbiont, — one of two organisms partaking of symbiotic relationship. 

Mutualism is a fomi of sjaiibiosis in which both s^^nbionts are in 
more or less measure benefited by the union. 

Commensalism is that form of sjinbiosis in which but one sjanbiont 
is benefited, while its co-symbiont is neither benefited nor harmed by 
the union. 

Helotism is a form of symbiosis in which one organism appears to 
enslave the other, enforcing it to labor in its behalf. The term is applied 
to such association in certain insects. 

Parasitism is that form of sjanbiosis in which one s^inbiont, for pur- 
poses of procuring food, or food and shelter, visits briefly, or takes up 
its abode temporarily or permanently, upon or within the body of its 
co-symbiont which is harmed by the union. The s^inbiont receiving 
the advantage is known as the parasite, to which the one injured is the 
host. 

Phytoparasites are parasites which belong with the vegetable 
kingdom. 



8 PARASITES OF THE DO:\IESTIC ANIMALS 

Zooparasites are parasites which belong with the aziimal kingdom. 

Optional Occasional Parasites are those which only fleetingly visit 
their hosts to oljtain nourishment, but are not dependent upon them for 
either nourishment or shelter. Example, mosquitoes. 

Obligate Occasional Parasites are those which do not permanently 
live ujjon their hosts, but are dependent upon them for nourishment and 
to some extent for shelter. Examples, fleas, bedbugs. 

Determinate Transitory Parasites are those in which the parasitism 
is hmited to a definite phase or phases in their life history, during which 
time the parasitism is oljligate and continuous. Examples, botflies, 
ticks. 

Permanent Parasites are those in which the parasitism extends from 
the haf chiiig of the <'Kg to the stage of reproduction in the adult. Exam- 
ples, lice, many entozoa. 

Fixed Parasites are those which cannot pass spontaneously from 
one host to another. Examjiles, larvse of botflies, Lmguatula, helmin- 
thes. 

Erratic Parasites are those which in their adult state may pass 
readily from one host to another of the same or different and widely 
.separated sjx'cics. I'Aaniples, mosquitoes, biting flies, ticks, leeches. 

Determinate Erratic Parasites are those which may pass from one 
host to another of the .same species, or a species closely allied to the one 
abandoned. Examples, lice, psoric Acarma. 

Monoxenous Parasites are (a) those the eggs of which are expelled 
by the host, the embryos, while still within the eggs, passing to a new 
host where hatching and development to the adult occurs. Example, 
Ascaris. 

(b) The eggs having been hatched, the larvae are noiuished in suitable 
conditions of moisture and temperature, but cannot undergo further 
development until they have reached the body of their host. Example, 
Hcmonchnx vontodun. 

Heteroxenous Parasites are (a) those which pass to their definitive 
host by an intermediate or transitory host, in which they cannot attain 
their complete development ; consequently, a reciprocal transmission 
between the.se hosts is essential to the development and propagation of 
the parasite. Examples, tapeworms, Plasmodium of malaria. 

(b) The eggs of the para.site are hatched in the !)ody of the host, the 
embryos invading the ti.ssues of the same indivitlual host and not at- 
taining the adult state until they have reached a second host. Example, 
Trichinella spiralis. 

Transmigration is a term applied to the passing of heteroxenous 
parasites from one host to another. 

Incidental or Stray Parasites are those which under natural condi- 
tions are occasionally found in unusual hosts. Examples, Gigantorhyn- 



FORMS OF PARASITISM 9 

chus hirudinaceus (specific in pig, incidental in man) ; Fasciola hepalica 
(specific in Herbivora, incidental in man) . 

Ectoparasites (Epizoa) are those which are parasitic to the surface 
of the bodj^, whether burrowing into the integument, living upon it, or 
only occasional visitors. Examples, scab mites, ticks, and other Acarina, 
lice, flies. All of the arthropodal parasites with scarcely an exception. 

Endoparasites (Entozoa) are parasites which enter the body of their 
host, inhabiting its alimentary canal, blood, and other tissues. Exam- 
ples, Linguatula, larvae of the botflies, and almost all of the helminths. 

Helminthes is a term under which are grouped all of the worms 
generally parasitic, with the exception of a small number in which the 
body is annulated. The group is not a natural zoological one and is 
used mostly in parasitology. 

In terms used to designate parasitic diseases it is customary to apply 
the name of the genus, or other group name to which the parasite be- 
longs, as the root, to which is added the suffix asis or osis. As for ex- 
ample : 

Pediculosis, the condition produced by the presence of lice upon 
the skin; Acariasis, the condition produced by the presence upon the 
skin of mites and other Acarina; Filariasis, the condition produced by 
Filaria. And thus we have Ascariasis from Ascaris, Oxyuriasis from 
Oxyiiris, Strongylosis from Strongylidse, Trichinosis from Trichinella, 
Taeniasis from Tseniidse, Fascioliasis from Fasciola, Helminthiasis from 
Helminthes, and Trypanosomiasis from Trypanosoma. 

In view of the many factors to be considered, the formulation of 
exact and limiting interpretations of terms bearing upon kinds of par- 
asitism is scarcely possible. It cannot be claimed for the above series, 
therefore, that it is entirely satisfactory as stated and defined. For our 
conceptions we must rely upon the behavior of the typical rather than 
the isolated or synthetic, and be content to regard any grouping based 
upon modes of parasitism as more convenient than exact. It is difficult 
to circumscribe parasitism; while we speak of the parasitic mode of life 
as a form of symbiosis, it may well be questioned whether such insects as 
mosquitoes and biting flies bear a true sjanbiotic relationship to their 
hosts; their fleeting visits certainly do not constitute the living together 
as usually implied by the term. Again, we may not be able to draw a 
distinct line between certain predaceous and certain parasitic forms. 
From the more general viewpoint, however, it may be repeated that all 
predaceous animals voluntarily, by the exercise of their powers of stealth 
and cunning, seize upon and aim to destroy their prey at once, feedijiig 
upon the body. There are parasites which use a degree of stealth in 
approaching their victims, as certain parasitic Diptera, though the 
invasion of the body of its victim hy the parasite is more often passive 
than voluntarj^ While the parasite may appropriate a share of the 



10 PARASITES OF THE DOMESTIC ANIMALS 

nutriment of its host or feed upon its host's tissues, it is detrimental to 
the parasite's welfare to destroy its host. To destroy the body of the 
animal harboring it would mean the sacrifice of the parasite's means of 
subsistence as well as in most cases its shelter. When the host animal 
dies its ijiternal parasites die with it, and, if it were not for the previously 
occurring transmission of their offspring to new hosts, the species would 
rapidly perish. Serious disturbance or death of the host due to its 
parasites is usually brought about by their presence in large numbers, 
in which case there is the operation of numerous pathogenic factors. 
A fata! termination may follow rapidly, but more often there are afebrile 
morbid phenomena running a prolonged course. In no case is the victim 
at once destroyed and wholly or in part devoured. 

The parasite is always smaller and weaker than its host, and in manj^ 
ca.ses its influence upon the latter is not observable. It may be said in 
general that the degree of injury will depend upon the following prin- 
cipal factors: 

Infliexce Ffon- the Host 

1. The Number of Parasites Present. — A tapeworm or one or two 
ascarids in the mtestines may not jiroduce a noticeable effect upon the 
host. If these parasites are numerous there may be serious disturbances 
in the host resulting from the deprivation of nutriment which has been 
appropriated by the infesting worms, from the toxins which they elab- 
orate, or a more acute effect may be brought about through obstruction 
of the bowel by large numbers of the parasites in mass. 

2. Their Location. — An encysted larva of the beef or pork tapeworm 
in its usual location will do no observable harm to its host, but if it 
should lodge in the eye or central nervous system it might give rise to 
serious disorders. As a rule, intestinal parasites are less harmful than 
those which invade the blood or resjjiratoi-y tract, while of the external 
]iaiasites. those which biu'rovv into the integument are more injurious 
than those living upon the surface. 

3. The Nature of their Food. — Any parasite which feeds upon the 
tissues of its host is more harmful than one which merely appropriates 
a share of the latter's ingested nutriment. The lilood-sucking worms, 
when present in considerable numljers. bring about serious depletive 
disturbances, while such worms as the adult ascarids, nourishing mainh' 
upon the residue of food materials, are, in general, less harmful. Sucking 
lice, armed with piercing mouth parts, are more disturl)ing to the animal 
harboring them than the l)iting lice which feed upon cutaneous debris 
and the products of their irritation. 

4. Their Movements. — Serious pathologic conditions may be 
brought about by the migrations of parasites or their change from a 
usual to an unusual position. Muscular trichinosis, the collective 



INFLUENCE UPON THE HOST 11 

effect of the movement of myriads of embryos of Trichinella spiralis, is a 
typical instance. An otherwise relatively harmless parasite may work 
its way into a duct, or, finding lodgment in an unusual organ, set up 
inflanmiatorj'- changes and abscess formation. Again, by verminous 
wandering, fistulous communications may be established between 
contiguous organs normally possessing no direct connection. 

5. Age of Host. — Young animals are predisposed to endoparasitic 
invasion. To forms which penetrate or are more or less migratory, the 
more tender tissues of the young offer less resistance than in older 
animals. Verminous bronchitis is a form of strongylosis observed almost 
exclusively in animals which are immature. The reduced vitality of 
old age invites the invasion of both external and internal parasites; 
there is not only a lessened ability to defend from attack, but reduced 
activities and secretions of the intestines, skin, and other organs de- 
crease the capability of eliminating either ecto- or entozoa. 

Such external parasites as mosquitoes, flies, ticks, and bedbugs are of 
greatest pathologic importance as disseminators of infectious diseases, 
acting either as direct carriers or as intermediate or definitive hosts of 
the infecting organism. Malaria, Texas fever, and forms of trypan- 
osomiasis are among diseases which are known to be spread only bj'' this 
means, while the possibilities as carriers of typhoid and other malignant 
infections engendered by the habits of the common house fly are well 
known. 

That Helminthes elaborate materials toxic to their host has been 
demonstrated in experiments with the isolated poisons. It is obvious 
that, in cases of heavy infestation especially, this toxic effect must be 
considerably contributed to by the products of decomposition of dead 
worms. 

Etiology; — So varied are the conditions that surround the propaga- 
tion and existence of parasites that the consideration of the causes of 
parasitic diseases is best embodied in chapters devoted to their particular 
occurrence. However, certain circumstances favoring parasitism may 
be here briefly considered. 

Crowded and unclean housing favors the propagation and spread of 
parasites of both man and domestic animals. For this reason lice and 
scab mites find their most favorable season in the winter months, when 
their transmission from animal to animal is facilitated and the reduced 
activities of the skin offer less resistance to their invasion. Pediculosis 
and the scab acariases are seldom seen, however, in stables that are 
well kept, or among animals where due attention is paid to cleanliness of 
the skin. The summer, on the other hand, is the season of attack Ijy 
adult parasitic Diptei'a, and it is during the months at pasture that 
ticks most rapidly iiroijagate and crawl upon their hosts. 

In helminthiasis the influences of environment as an etiologie factor 



12 PARASITES OF THE DOMESTIC ANIMALS 

are more subordinate to the mode of development of the infecting 
species. Sheep grazing upon low, marshy land and in the vicinity of 
ponds are more exposed to infestation with flukes, because there are 
present conditions essential to the molluscan intermediate host in which 
the fluke at the stage of the miracidium must find lodgment. Infestation 
of the pig or the ox with the larvae of the tapeworms of man is most 
likely to occur where untreated human excrement is used as a fertilizer, 
or where their food may otherwise be directly or indirectly contaminated 
with such material, while invasion of the human host with the adult 
worm only occurs after ingestion of the tissues of the larval host. The 
majority of ova of worms expelled by the host fail to find a new host, or 
meet with unfavorable conditions and are lost. Some, as those of 
ascarids, are very resistant and may find their proper host after months 
of exposure to destructive influences. Migration is facilitated to some 
extent where hatching takes place with the laying of the egg, as in the 
strongyles of the respiratory tract and m Trichinella. 

While much remains to be determined as to the life histories of many 
of the internal parasites, clinical experience indicates that low and wet 
pasturage, with access to stagnant collections of water, is a strong 
etiologic factor in helminthiasis, either as harboring possible aquatic 
intermediate hosts of the worms, or as a vehicle which, directly or by 
drainage, spreads infestation by dissemination of their germs. 



CHAPTER III 
PHYLUM I. ARTHROPODA 

While there are advantages in arranging a description of parasites 
according to their location, as those of the skin, those of the intestines, 
those of the liver, those of the circulation, etc., the fact that so man}' 
in their life histories pass certain stages Ln different organs and different 
species of hosts makes such an arrangement somewhat confused. It 
seems better, therefore, to treat of the natural history of each parasite 
in the parasite's order, essentially including such anatomical and zoolog- 
ical migrations as may be involved, while at the same time considering 
its pathogenic influences in these varying locations. 

Aside from the phjiioparasites, which are not included in this work, 
the parasites mfesting man and domestic animals are distributed among 
four grand divisions or phyla of the animal kingdom, which, in the order 
of their zoological grade, are Protozoa, Platyhelminthes, Coelhelminthes, 
and Arthropoda. The last named group contains most all of the external 
parasites and is the first to be considered in the pages to follow. 

As a foundation for the scientific control of parasitism and for the 
recognition of adaptations to its various forms, at least an elementaiy 
knowledge of the structure and habits peculiar to the phylum and its 
subdivisions to which the parasite belongs is of essential importance. 
Only the more prominent structural features upon which the separation 
of the different groups and their subgroups is based will be given here. 
For more detailed study the student is referred to an advanced text-book 
in zoology. 

The phylum Arthropoda includes such annuals as the crayfish, crabs, 
lobsters, spiders, centipedes, and insects. The body is provided with a 
hard or leathery external chitmous skeleton divided mto a number of 
segments demarcated externally by constrictions, each segment in the 
adult, or a certain number of the segments, bearing jointed appendages 
(Fig. 1). There are usually two or more body regions distinguished by a 
special modification of the constituant segments. In order that move- 
ments may take place between the segments of both the body proper 
and of the appendages, the cuticle at these points is thin and delicate 
(Fig. 9), forming joints which are protected by an overlappmg of the 
heavier chitmous armor. 

All arthropods periodically molt, the process consisting of the break- 
ing and casting off of the chitinous cuticle after it has loosened from the 



14 PARASITES OF THE DOMESTIC ANLAL\LS 

uiuieilyinii; tissue and a new cuticle has been formed. While the cuticle 
is at first thin and soft, later it Ijeconies hard and unyielding, therefore 
the nioltings are necessary for the accomniodation of growth and occur 
periodically as long as this growth continues. Chitin, to which the 
firmness of the cuticular exoskeleton is due, is an organic substance in 
which lime salts may be deposited, as occurs in the Crustacea. The 
skin is never ciliated, nor do ciliated cells occur in any other organs of 
the bodj^ 

The nuisculature (Fig. 9) consists of a large number of separate 
muscles passing from one segment to another and attached at their 
extremities to the inner side of the skin, their contraction bringing about 
movements of the segments of the body and appendages one upon the 
other. They may be attached by so-called tendons, which consist of 
invaginations of the cuticle surrounded by a corresponding invagination 
of the epitlei'iuis. The muscle fibers are striated and multinuclear. 

The digestive tract (Fig. 2) passes directly, or with little flexion, 
through the body, the mouth being at the anterior end and usually 
ventral, the anus posterior. Accessory organs, as salivary glands and 
liver, may or may not be present. 

Of the circulatory system (Figs. 2 and 3) the most constant portion is 
the heart, which is usually tubular and located dorsally. On each side of 
the organ are openings provided with valves through which the blood 
passes to be pi-ojielled forward. P^iom the large arteries the blood may 
pass directly into blood sinuses, or it may course through capillaries and 
veins, though the vascular system is never entirely closed. The blood is 
usually a colorless fluid with colorless amoeboid corpuscles. 

In aqviatic form.s (C'lustacea) respiration is by gills, while in the air- 
breathers it may he by tracheiP (Figs. 5 and 6), consisting of tubular 
ramifications from without to within the body, or Ijy peculiar infolding 
modifications of the integument functioning as lungs. In some of the 
lower forms respiratory organs are entirely absent, the function in such 
cases being difl'used over the entire body surface. 

In various spaces within the bodies of Arthropoda are frequently 
found fat botlies, a connective tissue the cells of which, richly laden with 
fat, serve as a store of nourishment. The fact that products of tissue 
metabolism, such as uric acid, have been found in the fat body, leads to 
the conclusion that it also acts as a place of storage for substances of 
excretion befoi'e their elimination by the excretory organs, which latter 
greatly vary in the different groups. In insects and arachnids these 
organs are represented by the Malpighian tubes, long glandular canals 
which open into the posterior portion of the digestive tract. 

The nervous system consists typically of a ventral chain of ganglia 
connected by a double longitudinal nerve cord. In well-developed seg- 
ments the ganglia are large, and a pair of gangha to each segment might 



ARTHROPODA 15 

be expected, as in the annelid worms. In the Arthropoda, however, 
there are differences due to fusion of the segments, in which case there 
is also fusion of their ganglia. Such fusion is usually accompanied by 
more or less shortening of the body, an e.xample of which is afforded by 
the spiders and crabs where the whole ventral chain unites in a single 
ganglionic mass. From the most anterior of the ventral gangha there 
spring two nerve cords which pass on either side of the esophagus to 
unite above it with the paired cerebral ganglion or brain, lying in the 
head. This ganglion remains distinct, its dorsal position preventing its 
fusion with ganglia of the ventral chain. 

Oi the sense organs the most highly developed are the eyes, which are 
compound (Fig. 6), or appear as simple ocelli. In many arthropods 
there are both of these forms, while others are provided only with ocelli, 
and in some arthropods eyes are absent. In the compound eyes the 
cuticle covering them is divided into hexagonal facets, the number of 
which varies with different groups from a dozen to two thousand or 
more, each of these areas corresponding to a small chitinous lens. The 
compound eyes are two in number, while the number of ocelh varies. 
The latter are very small and have their highest development in the 
spiders. 

With rare exceptions the sexes are separate, and reproduction is 
generallj' by fertilized eggs, though parthenogenesis occurs, in some 
cases having a certain relationship to the life history. Usually the sexes 
can be readily distinguished by the difference in size and by various 
modifications of the appendages. 

Of the subgroups of the phylum Arthropoda only those containing 
parasitic species of medical interest will be considered in this work. 
These are included in the two classes Insecta and Arachnida, which, 
with scarcely an exception, contain all of the external parasites. It is 
not correct, however, to say that the arthropodal parasites are exclusivelj^ 
external, as certain insects and arachnids pass a phase of their develop- 
ment within the bodies of their hosts. 

Class I. Insecta 

Arthropoda (p. 13). — In number of species the insects constitute 
the largest of all animal groups. The body is essentially segmented, and 
is divided into three regions, — head, thorax, and abdomen, which are 
distinctly marked off from each other (Fig. 1). 

The head is usually freely movable at its junction with the thorax, 
and typically bears on each side a compomid eye (Figs. 1 and 7). be- 
tween which there nraj' be a varying number of simple ocelli. 

Ai'ising from the head are a pair of antennae which consist of seg- 
ments varying in size, shape, and number accordmg to species. 



16 



PARASITES OF THE DOMESTIC ANIMALS 



The mouth parts (Fig. 4) undergo great modification, though all may 
be referred to a common type. This is well presented in its primitive 

condition by the grasshopper, 
in which we have the labrum, 
or upper lip, represented by a 
broad unpaired plate situated 
in front of the mouth. Under 
the labrum is a pair of strong 
jaws, the mandibles, each con- 
sisting of a single unsegmented 
piece with a cutting inner edge, 
the two having a latei-al move- 
ment. Following the mandibles 
is the first pair of maxillae which 
are prehensile and gustatory in 
function. These have a num- 
ber of joints and bear curved 
and segmented palpi. The sec- 
ond pair of maxillse are fused 
to form a single plate, — the la- 

FiG. 1. — Diagram of an Insect, with Head and bium, which is accessory in func- 




Thoracic Segments Disarticulated: a, head 
bearing compound eyes, simple ocelli, and 
antennfe; b, prothorax; c, mesothorax; d, meta- 
thorax; c, abdomen; f, ovipositor. The pro-, 
meso-, and metathorax each bear a pair of legs; 
the meso- and metathorax each a pair of wings. 
1, Coxa; 2, trochanter; 3, femur; 4, tibia; 5, tar- 
sus, terminating in a claw (after Orton, by j^j-.r q^ ^J^g mOUth 
Dodge; Copyright, 1894, by Harper & Brothers). 



tion to the first pair of max- 
illae, and, like the latter, bear a 
pair of segmented palpi. The 
labium forms the posterior and 
the labrum the anterior bound- 



segments, an anterior, 



The thorax (Fig. 1) has three 
the prothorax, a middle, — the mesothorax, 




Fig. 2.- — Diagram of the Principal Internal Anatomical Parts of an 
Insect: m, mouth; cr, crop; st, stomach; i, lower portion of intestine; 
a, anus; h, heart; s, salivary glands; c, cerebral gangUon; n, ventral 
ganglion; Mp, Malpighian tubules; o, ovaries; g, genital aperature (after 
Boas, by Kirkaldy & Pollard). 



and a posterior, — the metathorax. 
somewhat fused. 



The last two of these are usuallv 



ARTHROPODA 



17 



There are three pairs of legs, each thoracic segment bearing one paii- 
(Fig. 1) . The leg is divided into five articulated parts, — coxa, trochanter, 
femur, tibia, and tarsus. The attachment to 
the body is by the short coxa, to which is joined 
the trochanter which is also short. Following 
the trochanter are two long segments, — the fe- 
mur and tibia, the former considerably thicker p^^^ 3 . 
than the latter and containing the muscles. The sect's Heart: 

tarsus, or foot, follows the tibia, and consists of between two chambers ;^ V 
' ' 111. valves (after Boas, by Kirk- 

a number 01 short segments, the last bearmg aidy & Pollard), 
hook-like structures, or claws. 

Usually there are two pairs of wings arising dorsallj^ from the meso- 



Diagram of In- 
constriction 




Fig. 4. — Mouth-parts of Locust, a biting insect: Labrum, or upper-Hp, 
above, on each side of which are the mandibles, or upper pair of jaws. 
Labium, or under lip, with labial palpi below. Ma.xillae. or lower pair of 
jaws, with maxillarj- palpi, to right and left (from photomicrograph of 
mounted specimen, by Hocdt). 

and metathorax (Fig. 1). They consist, when fully developed, of two 
closely apposed chitmous outgrowths, between which are extensions of 



18 



PARASITES OF THE DOMESTIC ANIMALS 



the blood sinuses and tracheas. Sometimes the anterior, sometimes the 
posterior pair is the larger, and both may be flexible and adapted for 
flight. In some insects (beetles) the anterior pair is modified to form 
wing-shields, or elytra, which are hard, but 
slightl.y flexible, structures serving to cover 
and protect the posterior wings during rest. 
Some insects possess Ijut one pair of wings 
(dipterous), while in others wings are entirely 
absent (apterous). 

The aVjdomen is segmented, the number of 
segments varying with different groups. Each 
segment consists of two cuticular plates (Fig. 6), 
the dorsal tergite and the ventral sternite, 
which are united laterally by a softer mem- 
brane, the pleurite. There are no abdomuial 
limbs or limb-like appendages. 

Respiration is by tracheae (Fig. 5), a system 
of tubes containing air. These communicate 
with the outside by 
the spiracles (Fig. 
()), small svnnnet- 



FiG. 5. — Diagram show- 
ing the chief trunk.s of the 
tracheal sy.steiii of an in- 
sect (after Boas, hy Kirk- 
aldy & PollanI). 





Fig . 6. — Abdomen of Lo- 
cust, s howing Spiracles 1, 2, 3, 
4. 5, 6, 7 and 8, one on each side 
of each of the abdominal seg- 
ments; A, auditory sac (drawn 
in part from Packard's Zool- 
ogy). 



r 1 c a 1 1 y aispose( 

()])enings locatec 

lat(>rally, one pair 

on the meso- and 

one pair on the 

metathorax and a 

]iair on each of the 

abdominal segments 
except the mo.st jiosterior. Just inside of the spiracles the tracheae are 
usually united by longitudinal trunks from which are given off fine 
branches which ramify and anastomose within the bod^^ Respiration 
is effected by abdominal movements of contraction and expansion. 

Insects are mostly oviparous. In some the developed embryo is 
released from the egg while still within the body of the parent, or this 
may occur .just as the egg is extrudeil. There are also pupiparous forms 
where the yovmg ]3ass fi'om the Ijodv of the female ready to enter the 
ptipal stage in their development. 

In order that the newly hatched larvae may be supplied with nourish- 
ment, the eggs are generally deposited where suitable food is present. 
In many insects oviposition occurs by means of an ovipositor, a tube- 
like organ which is developed from the posterior abdominal segments 
and which may ]jroject fi-ee from the body or may be retracted into it. 
In the Hymenoptera the ovipositor may be modified to serve as a sting, 



ARTHROPODA 



19 




a weapon of defezise provided with poison glands. From its nature the 
sting is essentially only possessed by the females. . 

Some insects on leaving the egg develop directly to the adult stage, 
the larva in most cases differing from the adult prin- 
cipally in the absence of wings. In such cases there 
is a slight change of form with successive molts, 
the wings being ultimately acquired. Here the meta- 
morphic process is not thorough, and is therefore 
referred to as incamplete vietamorphosis. The ma- 
jority of insects when hatched from the egg bear 
no resemblance to the adult, and there is no observ- 
able gradual approach to this form. The larva is 
characteristically worm-like and an active and vora- ^-^^ j-,gg^ shewing 
cious feeder, a number of molts occurring with the compound eyes, the 
increase in size during this stage. There then **^'^'^ oeeii^and the 
intervenes between the larval and adult stages a ged (after Orton, by 
period of pupation, during which the animal is quies- Dodge; Copyright, 

cent and a series of changes ^f^tkJ^). ''"''" * 

occur in the body. At the 

conclusion of these changes the pupal case 

splits and the imago emerges, which, with 

the unfolding of the ap- 
pendages and hardening 

of the cuticle, has in all 

essentials developed into 

the complete sexual 

adult. In this form 

of development the 

changes are distinct, and 

the process is referred 

to as complete meta- 
morphosis (Fig. 8). 
The duration of life 

in insects, including the 

stages of the egg, larva, 

pupa, and adult, usually- 

does not extend beyond 

a year. With quite a 

numljer it is much 

shorter than this, while 

with others it may be a 

matter of several years, 

an extreme example of 

larval longevitv being 





Fig. 0. — Diagram of termi- 
nal segments of arthropod leg, 
with muscles, a, articulation; 
f. flexors; e. extensors (after 
Boas, by Kirkaldy & Pollard). 



Fig. S. — Metamor- 
phosis of the House Fly, 
showing oval, larval, 
pupal, and adult stages. 
On the right is an en- 
largement of the foot; 
on the left, the foot pad, 
showing sticky, glandu- 
lar hairs; on upper left, 
a tsetse fly (from photo- 
graph of drawing by 
author). 



20 PARASITES OF THE DOMESTIC ANI]\IALS 

afforded by the seventeen-year cicada. Most of the insect life is occupied 
by the larval stage, during which the greatest growth takes place. With 
a few exceptions, as honey bees and ants, the period of the adult is short, 
in some cases a few days or even hours. The life of the adult is de- 
voted to the activities concerned in reproduction, and the insect usually 
dies when this is accomplished. 

Of the class Insecta the five following orders contain parasites of 
medical importance: 

Order I. Diptera — Flies, gnats, and mosquitoes. 

Order II. Siphonaptera — Fleas. 

Order III. Siphunculata — Sucking lice. 

Order IV. Mallophaga — Biting lice. 

Order V. Hemiptera — Bedbugs and allies. 

Classification of Parasites of the Class Insect.a. 

Phylum I. Arthropoda. P. 13. 
Class A. Insecta. P. 15. 
Order 1. Diptera. P. 23. 

Family (a) Culicidae. Mosquitoes. P. 24. 
Genus and Species: 

Culex pungens. Pp. 25, 26. 
Anopheles cjuadrimaculatus. P. 26. 
A. punctipennis. P. 28. 
Ades calopus. P. 29. 
Family (b) Simuliidse. Buffalo gnats. P. 31. 
Genus and Species: 

Simuhum pecuarum. Animals attacked, equines and cattle. 
P. 32. 
Famil}' (c) Tabanidic. Horseflies, gadflies. Animals attacked, 
equines, cattle. P. 35. 
Genus and Species: 

Tabanus atratus. P. 35. 
T. lineola. P. 36. 
Family (d) Muscidse. House fly and allies. P. 37. 
Genus and Species: 

Musca domestica. Injurious to man and domestic annuals 

by irritation and contamination. P. 37. 
Stomoxvs calcitrans. Animals attacked, equines and cattle. 

P. 39! 
L\'perosia irritans. Animals attacked, cattle. P. 41. 
Glossina palpalis. Animals attacked, man, and domestic 

and wild animals. P. 44. 
G. morsitans. Animals attacked, same. P. 44. 
G. longipalpis. Animals attacked, same. P. 44. 



ARTHROPODA 21 

Chrysomyia macellaria. Larvae attack flesh and mucous 

surfaces of man and lower animals. P. 50. 
Sarcophaga sarraceniee. Larvae attack fresh meat and 

wounds of animals. P. 52. 
Calliphora vomitoria. Larvae attackfresh and decomposing 
meat and wounds. P. 52. 
Family (e) Hippoboscidae. P. 47. 
Genus and Species: 
Melophagus ovinus. Host, sheep. P. 47. 
Family (f) (Estridae. Botflies. P. 53. 
Genus and Species: 

Gastrophilus intestmahs. Host, equines. P. 53. 
G. hemori'hoidalis. Host, equines. P. 57. 
G. nasalis. Host, equines. P. 57. 
Hypoderma lineata. Host, cattle. P. 57. 
H. bovis. Host, cattle. P. 58. 
(Estrus ovis. Host, sheep. P. 62. 
Order 2. Siphonaptera. P. 65. 

Family (a) Pulicidas. Fleas. P. 65. 
Genus and Species: 

Ctenocephalus canis. Host, dog. P. 65. 
C. felis. Host, cat. P. 65. 
Pulex irritans. Host, man. P. 65. 
Order 3. Siphunculata. Sucldng lice. P. 70. 
Family (a) Pediculidae. P. 70. 
Genus and Species: 

Haematopinus asini. Host, equines. P. 73. 
H. eurysternus. Host, cattle. P. 74. 
Linognathus vituli. Host, cattle. P. 74. 
L. pedalis. Host, sheep. P. 76. 
L. stenopsis. Host, goat. P. 77. 
Haematopinus suis. Host, hog. P. 77. 
Linognathus piliferus. Host, dog. P. 78. 
Pediculus humanus. Host, man. P. 79. 
P. eorporis. Host, man. P. 79. 
Phthirius pubis. Host, man. P. 79. 
Order 4. Mallophaga. Biting lice. P. 7L 
Family (a) Philopteridse. P. 7L 
Genus and Species: 

Trichodectes equi. Host, equines. P. 73. 

T. pilosus. Host, equines. P. 73. 

T. scc^ilaris. Host, cattle. P. 75. 

T. sphaerocephalus. Host, sheep. P. 76. 

T. climax. Host, goat. P. 77. 



22 PARASITES OF THE DOMESTIC ANIMALS 

T. latus. Host, dog. P. 78. 

T. subrostratus. Host, cat. P. 79. 

Goniocotes gallinse. Host, chicken. P. 82. 

G. gigas. Host, chicken. P. 82. 

Lipeuius caponis. Host, chicken. P. 83. 

L. heterographus. Host, chicken. P. 83. 

Goniodes styhfer. Host, turkey. P. 84. 

Lipeiirus nieleagridis. Host, turkey. P. 84. 

Pliilopterus icterodes. Hosts, ducks and geese. P. 84. 

Lipeurus anatis. Hosts, ducks and geese. P. 84. 

Philopterus cygni. Host, swan. P. 86. 

Ornithononius cygni. Host, swan. P. 86. 

Cioniocotcs compar. Host, pigeon. P. 86. 

(ioniodes daniicornis. Host, pigeon. P. 86. 

Lipeurus coiunibse. Host, pigeon. P. 86. 
Family (b) Liotheida. P. 7L 
Genus and Species: 

Menoinnn trigonocephahun. Host, chicken. P. 83. 

M. biscriatuni. Host, turkey. P. 83. 

Trinotuni hn'iduni. Hosts, ducks and geese. P. 84. 

T. Htuiatuni. Hosts, ducks and geese. P. 86. 
Order 5. Heiniptera. P. 89. 
Family (a) Cimicida?. P. 90. 
(ienus and Species: 

Ciniex lectularius. Hosts, man, poultry, etc. P. 90. 



CHAPTER IV 

MOSQUITOES AND GNATS 

Order I. Diptera. — Insecta (p. 15). The dipterous insects have only 
the anterior pair of wings developed, the posterior pair being repre- 
sented by rudimentan' structures called halteres, or balancers, which 
are supposed to function as organs of balance. In some parasitic forms 
(sheep "tick," bat fly) wings are entirely wanting. 

The head, thorax, and abdomen are sharply defined. The mouth 
parts are adapted for sucking, the haustellum, or suckuig tube, being 
formed by the labium and labrum, within which lie the mandibles and 
maxillae, which may be modified into blade-like structures for piercing. 
With this structure the insect sucks the juices of plants or penetrates the 
skin of animals and feeds upon their blood. In the flies the antennae are 
short, consisting of but three well-developed joints. The three thoracic 
segments are frequently fused, and the tarsi have five segments. 

Metamorphosis is complete. The larvae are apodal grubs, maggots, 
or wrigglers, the latter aquatic (mosquitoes). 

Parasitism. — The dipterous group of insects includes a number of 
species varjdng in their grade of parasitism from optional occasional to 
obligate occasional and permanent. They are chiefly of importance 
from the medical viewpoint as carriers of bacterial and animal parasitic 
infection, investigations within recent years well establishing the fact 
that certain serious and often fatal diseases of man and domestic animals 
are spread "by these insects either as essential hosts or as direct carriers 
of the infecting organism. As essential hosts a part of the development 
of the pathogenic organism must essentially be imdergone in the insect. 
As direct carriers they may inoculate directly into the blood with con- 
taminated piercmg or biting mouth parts, or they may simply trans- 
port disease germs upon their bodies and appendages, contaminating 
wounds, food, or any object upon which they may alight. 

As blood-sucking pests and sources of torment in the habitations of 
man and in the fields and stables of his live stock, many of these two- 
winged insects are of very considerable economic as well as pathologic 
importance. In view of all that at the present time can be charged 
up against them, they are well worthy of the mcreasing attention they 
are receiving with a view to their more effectual control. 

Of the families of the order Diptera containing parasitic species, six 
are here considered, as follows: 



24 



PARASITES OF THE DOMESTIC ANIMALS 



Family I. Culicidse — Mosquitoes. 

Faniih' II. Simuliidse — Buffalo gnats. 

Family III. Tabanidse — Horseflies. 

Family IV. IMuseidse — House fly and allies. 

Family V. HiiDpoboscidae — Sheep "tick." 

Family VI. CEstridse— Botflies. 

Family I. Culicid^; Mosquitoes 

Dipt era (p. 23).^^The mosquitoes are slender-bodied Diptera with 
narrow wings which have a distinctive frmge of scale-like hair upon 
their margins, and in most cases also on each of the wing veins. In the 
female the proboscis is long, slender, and adapted for piercing. The 




Fig. 10. — Egg-ma.ss of Culex punge?is, above; young lan-a, greatly enlarged, at right; 
young larvie, less enlarged, below; enlarged eggs above at left (after Howard, Bui. No. 4, 
Bureau of Entomology, Dept. of .\gr.). 

males do not suck blood, differing from the females in the absence of 
the piercing .stylets and in the possession of plumose antennae. 

Mosquitoes have an adaptation to a very wide range, flourishing 
equally as well in the frigid regions of the Arctic and Antarctic as in the 
humid heat of the tropics. Until comparatively recent years few species 
were known, but more intensive study, in view of their importance as 
carriers of disease and as pests of man, has brought the mosquito fauna 
of the world up to about one hundred genera including seven himdred 
species, of which there are about fifty known in the United States. 

Breeding Habits. — In the larval stage all the known mosquitoes 
are aquatic, but such differences occur in their life histories and habits 



MOSQUITOES AND GNATS 25 

that no one species will serve as typical of the group. In observations 
conducted by L. 0. Howard at Washington, D. C. (1900 Rept.), upon 
the species C^dex pungens it was determined that the eggs were laid upon 
the water surface in masses of a variety of shapes, often described as 
boat-shaped because a common form is that of a pointed ellipse (Fig. 10). 
The number of eggs in each mass varied from two hundred to four hun- 
dred, all arranged perpendicularly and in longitudinal rows. The in- 
dividual eggs are slender, somewhat pointed at the tip, and at the bottom 
broader and blunt, having a length of 0.7 mm. and a diameter of 
0.16 mm. at the base. 

It has been demonstrated that under the advantageous conditions 
of the warm summer months eggs may hatch in less than a day from the 
time they are deposited. The larvse, issuing from the under side of the 
egg mass, are elongate, with head, thorax and abdomen distinct, the 
head bearing prominent antennae each consisting of a smgle segment. 
About the mouth is a mass of prehensile filaments. The abdomen is 
segmented, and respiration is by tracheae which open at the apex by 
means of the anal siphon. They appear to undergo four molts, and, 
under favorable conditions, may be transformed into pupae in about 
seven days. Studied at a period when the larva is nearly full grown, 
it is seen to remain near the surface of the water with its respiratory 
tube at the exact surface and its mouth below receiving food which is 
directed to it by the rotary movements of the mouth filaments. Occa- 
sionly the larva descends below the surface, but, by a series of wriggluigs, 
quickly returns. The return is only accomplished by considerable 
exertion, as, once below the surface, the tendency of the larva is to sink 
rather than to rise. If, therefore, for any reason it is unable to suffi- 
ciently exert itself to again reach the surface, it will perish. The efficacy 
of the film of oil spread upon the water may be thus explamed; it not 
only prevents access to the air, but, by its deleterious effect, renders the 
larva unable to exert sufficient muscular force to recover the position 
necessary for respiration and buoyancy. 

The transformation to the pupal stage, occurring under favorable 
conditions about the seventh day, is marked by a great enlargement of 
the thoracic segments (Fig. 11). Here the reverse of the just described 
physical phenomena obtains; the pupa is lighter than water, and, unlike 
the larva, effort is required to sink rather than to rise. It remains mo- 
tionless at the surface, when disturbed descending to the bottom by 
violent wrigglmgs. As soon as these exertions cease it will again grad- 
ually rise. The differential structure of the pujja is noticeable in the 
( nlargement of the thorax, and in that the air tubes no longer open at 
the abdominal apex, but through two ear-like processes on the thorax, 
the pupa remainmg u]:)right at the water's surface instead of head down- 
ward as in the larval stage. Since the adult insect emerges from its 



26 



PARASITES OF THE DOMESTIC ANIMALS 



pupal case at the thorax, there is an apparent adaptaliiHt\' in this re- 
versal of position. 

The common house or "rain barrel" mosquito of the Northern 
United States, Culex pungens (Fig. 12), breeds throughout the summer, 
broods developing wherever there may be standing water, as in pools, 
troughs, cans, discarded bottles, gutters, etc. The adults of this species 
may pass the winter in the shelter of darkened retreats, such as the 
cellars of houses, behind furniture, outbuildings, and wood piles, 
emerging from their hibernation in the spring to deposit their eggs. 
Many first spring broods in temperate climates hatch from eggs that 
have been carried over the winter months, the eggs seeming to stand 
desiccation in dry locations to promptly hatch in pools left by the spring 




Fig. 11. — Pupa of Culcx pungens at left; pupa of Anopheles quad- 
rimaculatus at right — greatl.v enlarged (after Howard, Bui. No. 25, 
Bureau of lOntoniolog.v, Dopt. of Agr.). 

rains, or even in water from melting snow during the warmer days of 
late winter. 

In refutation of the assertion often made that mosquitoes cannot 
ovulate without a meal of warm blood, it has been demonstrated in 
experiments upon some of our common blood-sucking species that fe- 
males as well as males can not only be kept alive for a long period when 
given access only to ])lants, but will, under such conditions, repeatedly 
bi'eed. 

Pathologic Importance. — While their preference for blood has made 
them of ))rinuuy general interest as pests in the habitations of man, 
mosquitoes are of the greatest importance medically, not only as possible 
direct transmitters of disease, but as specific bearers of infection, bring- 
ing al>out such diseases as malaria, yellow fever, and possibly filariasis. 
There have been many convincing demonstrations that malaria is 
transmitted exclusive!}' by the bite of mosquitoes, only, however, b}' 
species belonging with the anopheles group, of which Anopheles quadri- 



MOSQUITOES AND GNATS 



27 




Fig. 12. — Culex puugens: a, female, from side; b, male, from above; c, front 
tarsus of same; d, middle tarsus; e, hind tarsus: f, genitalia of same, i. seales from 
hind border of wing; h. scales from disk of wing — enlarged (after Howard, Bui. 
No. 4, Bure.au of Entomolog.v. Dept. of Agr.). 



28 



PARASITES OF THE DOMESTIC ANI1VL4LS 



maculatus (Fig. 13) and A. punctipennis have been most often observed 
in the United States. While elaborate kej's and tables are necessary even 
to the entomologist for more exact differentiation, it is not a difficult 
matter to decide whether a mosquito is or is not a transmitter of malaria, 




Fig. 13. — Anopheles quadrimaculatus: Adult: male at left, fe- 
male at right — enlarged (after Howard, Bui. No. 25, Bureau of 
Entomology, Dept. of Agr.). 

the two genera Culex and Anopheles bemg readily distinguished by the 
followuig more prominent characteristics: 

The adult Culex, when at rest upon a wall, u.sually holds the body 




Fig. 14. — .\nopheles at left, Culex at right — enlarged (after Howard, Bui. No. 25, 
Bureau of Entomology, Dept. of Agr.). 

parallel with the wall, or with the abdomen slightly inclined toward it, 
the angle formed by the abdomen with the head and thorax giving a 



MOSQUITOES AND GNATS 



29 



hunchback appearance. The proboscis projects forward but not suffi- 
ciently so as to be on a hne with the axis of the body (Fig. 14). The 
palpi m the female are short, m the male usually long. The wings, as a 
iTile, are without spots. 

Adults of the anopheles group when thus at rest hold the bodj^ at an 
angle of about fort.v-five degrees with the wall's surface, the abdomen 
directed outward (Fig. 
14). The proboscis 
projects forward on a 
line with the axis of 
the body. In both 
sexes the palpi are 
about as long as the 
proboscis. The wings 
are usually spotted. 

The larva of Culex, 
when at the surface 
of the water, rests in 
an oblique or vertical 
position with the re- 
spiratory tube at the 
exact surface (Fig. 15). 

The resting larva of 
Anopheles floats in a 
horizontal position just 
beneath the surface. 
There is no respiratoiy 
tube, the spiracles 
opening on the eighth 
abdominal segment 
which is applied to 
the surface (Fig. 15). 

Eggs of Culex are de- 
posited upon water in 
masses, the rafts of eggs 
often being more or less 
boat-shaped (Fig. 10). 

Anopheles lay their eggs upon water unmassed, the eggs floating 
singly by lateral expansions (Fig. 16). 

The mosquito breeding in our Southern States which carries yellow 
fever from man to man, ^des calopus (Stegomya calopus, S. fasciata), 
is rather peculiarly marked. Upon each side of the thorax is a broad, 
silvery, curved Ime, between which there are two parallel median lines 
and a slender discontinuous line, the whole pattern presenting somewhat 




Fig. 15. — ^At top, half grown larva of Anopheles in 
breathing position, just beneath the surface film. At 
bottom, half grown larva of Culex in breathing position 
— greatly enlarged (after Howard, Bui. No. 25, Bureau 
of Entomology, Dept. of Agr.). 



30 



PARASITES OF THE DOMESTIC ANIMALS 



the shape of a lyre. At the base of each abdominal segment is a narrow, 
silvery band, while on each side there is a silvery spot. At the base of 
each .segment of the black legs there is a distinct white band. 

Highly domestic, this species will breed in collections of water about 
and within the habitations of man, the larvae often being found in small 
hou.sehold water receptacles, such as flower pots, vases, etc. Of its 
habits acquired I)y long association with man, Howard thus speaks: "It 
approaches i^tealthily from behind, retreating upon the slightest alarm. 




Klii. 16. — Group of PKKs of .Xnopheles quadrimafulatus as they appear resting 
naturally on the surface of the water — enlarged (after Howard. Bui. No. 25, 
Bureau of Entomology, Dept. of .\gr.). 

The ankles and, when one is sitting at a tal>le or desk, the under side of 
the hanils and wrists are favorable points of attack. It attacks silently, 
whereas otlier mosquitoes have a pii)ing or hunnniiig note. The warning 
sound has doubtless l)een supiiressed in the evolutionary process of its 
adaptation to man. It is extremely wary. It hides whenever it can, 
concealing itself in garments, working into the pockets and under the 
lapels of coats, and crawling up under the clothes to bite the legs. In 
houses it will hide in tlark corners, mider picture moldings and behind 
the heads of old-fashioned bedsteads. It will enter closets and hide in 
the folds of garments." 



MOSQUITOES AND GNATS 31 

Effect upon Live Stock. — That mosquitoes are a source of much 
annoyance and actual suffermg to Hve stock can be attested to by stock- 
men. Horses and cattle pasturing upon low lands and amid vegetation 
where the insects abound are especially exposed to attack, the pests 
often hovering about them in clouds, while upon the bodies of the 
animals large numbers may be seen with abdomens engorged with the 
blood of their victims. Loss of condition and the falling off of produc- 
tiveness in dairy herds must essentially follow this interference with 
their pasturage and comfort. 

Control. — The most effectual preventive measures dealing with mos- 
quitoes are those directed against the larvae. The abolition of breeding- 
places being of first importance, all receptacles for standing water, such 
as rain barrels, cans, vaults, gutters, etc., should be removed, covered, or 
otherwise made impossible to access and propagation of mosquitoes. 
Pools should be drained, or, if this is not feasible, may be treated with 
kerosene; or small fish, which feed upon the larvse, may be introduced 
into the mosquito-breeding ponds. The quickest and most satisfactory 
way to destroy larvse and pupae is by the formation of the kerosene 
film upon the water's surface. The oil is best applied for this purpose 
as a spray, or, if but a small area is to be treated, it may be thrown upon 
the surface and the water then vigorously stirred. About one ounce of 
kerosene to fifteen square feet of water surface will be sufficient, and this 
application should be repeated at intervals of about three weeks. 

Such measures are directed only against local species, and, essentialh'', 
there must be community action for it to be effective. Migratory forms, 
such as are bred in the marshes near our coasts, cannot thus be reached, 
their eradication constituting a problem demanding state control. 

For indoor protection in mosquito-infested districts, screening is of 
course essential. In spite of the most thorough screening, however, 
mosquitoes will enter in various wa.ys, as through openmg doors and upon 
the clothing of persons passing in. As remedies against those which 
have gamed access to houses various kinds of repellents are used. Burn- 
ing pyrethrum powder will often rid a I'oom of mosquitoes, a convenient 
method being to sprinkle the powder upon a heated shovel; or small 
cones may be molded from the dampened powder and, after drying, 
burned. Oil of^ pennyroj^al or citronella applied to handkerchiefs or 
lightly touched to the hands and face, though objectionable to some, 
will usually insure a peaceful night agamst the pests. 

Family II. Simuliid.e 

Diptera (p. 23). The flies of this family are known as black flies, 
black gnats, or buffalo gnats, the latter name derived from their peculiar 
humpljack appearance. They are dark coloied, with short thick body. 



32 



PARASITES OF THE DOMESTIC ANIINIALS 



short eleven-segmented antennae, no single eyes, broad wings, and stout 
legs. Only the females are provided with piercing mouth parts. 

The larvae, so far as known, are aquatic. The eggs are deposited in a 
compact layer upon some object, usually rock, near the surface of a 
flowijig stream. Upon hatching the larvae drop into the stream and live 
attached to sticks, stones, or other objects under the surface of swiftly 
rimning water. They may detach themselves and move about in a 
looping manner similar to that of the measuring worm, or they maj- 
be carried by the current for considerable distances. Respiration is 
carried on In' gill-like processes. 

SiMULIUM PeCUARUM 

The Southern Buffalo Gnat (Fig. 17). Simuliidae (p. 31). The adult 
female is nearl\' a quarter of an inch in length, the male somewhat 

smaller. The color of the body is 
black, and it is covered with light 
brown hairs which are arranged upon 
the thorax in such a manner as to give 
a longitudhial striped appearance, the 
abdomen showing upon its dorsal side 
a broad grayish stripe widening out 
toward the abdominal apex. The 
male notably differs from the female 
in that the eyes are much larger and 
join each other in the middle line. 
The individual facets on the upper 
part of the ej-e are considerably lai'ger 
than those of the female. 

The larva (Fig. 18) agrees in gen- 
eral appearance with that of other 
species of Simulium. It is about 
three-eighths of an inch in length, 
twelve-segmented, somewhat con- 
stricted in the middle, enlarging to- 
ward both ends. The posterior end 
is the larger and is somewhat club- 
shaped. In addition to the mouth, 
the head possesses two fan-shaped bodies which are prehensile ui func- 
tion. On the top of the last abdominal segment there are rows of 
booklets, while in the vicinity of the rectum are organs of respiration 
consisting of three tentacles to which the large tracheae lead. 

The pupa (Fig. 19) has a peculiar tuft of respiratory filaments starting 
from each side of the thorax. The upper portion of the pupal case is 
open, exposmg the head and permitting the respirator}' filaments to 




Fig. 17. — f^imulium pecuarum, female 
— pnlargpd (after Osboni, Bui. No. .5, 
Bureau of EntomoloKy, Dept. of Agr.). 



MOSQUITOES AND GNATS 



33 





Fig. is. — Si- 



have free access to the water. The pupa is firmly attached to sticks, 
leaves, or other submerged objects. On emei'giug from the pupal case 
the fly at once rises to the surface and, expanding its 
wings as it runs upon the water for a short distance, flies 
swiftly awa}'. 

Occurrence and Effect. — The buffalo gnat has been 
found in Alaska and throughout the Eastern United 
States, but appears in greatest numbers in the South, 
especially about the mouths of rivers and creeks. During 
the worst years the whole of the Lower Mississippi Valley 
as far north as St. Louis may be invaded. 

The attacks by swarms of this bloodthirsty and vic- 
iously active insect upon southern live stock is a source 
of serious injurj' and loss. Cattle and horses will mani- 
fest the presence of the swarms by frantic efforts to de- 
fend agamst the attack, cattle rushing wildly about and 
horses and mules trying to escape by running away. 
The most destructive raids of the Hy usually occur in 
the months of March and April. They are exceedinglj^ 
swift in their flight, darting at their 
victims in search of a suitable place to mulium peeua- 
draw blood, and in their bite instilling f"™' }^'^''r^~^'^' 

,^ . , ,. . ° larged (after Os- 

a poison. Many animals die from ex- bom, Bui. No. 5, 
haustion, combined with the toxic Bureau of Ento- 
effects of the poison from the bites. '^f°f^'' ^'^p*' °^ 
Bronchitis and pneumonia, resulting 
from the inhalation of large numbers of the insects 
from which the exhausted animal becomes totalh^ 
unable to defend itself, may also contribute to the 
conditions leading to its miserable death. 

Control. — Outbreaks in heavily infested districts 

may be lessened m frequency and severity by the 

clearing out of logs and other debris in the beds of 

streams, thus reducing the number of objects for 

Bui. No. 5, Bureau of attachment of the larvse. Unlike those of the mos- 

Entomology, Dept. of ^^jj^^^ ^^^^ j^^^.^,^ ^j Simulium thrive best in swiftly 

running and well aerated water, therefore the re- 

mo\'al of any submerged object causing shallow and swiftly moving 

water reduces the possibilities for breeding at this jjoint. 

Protection. — The black gnat dislikes smoke, therefore, as prevention 
against its attacks in fields and liarnyards, the maintenance of smudges 
is of value. Other repellents, such as fish oil, oil of tar, or other oleagin- 
ous and resinous substances, either singlj' or in combination, are 
applied to the surface of the body, affording a measure of protection 



Fig. 19. — SimuUum 
peeuarum, pupa — en- 
larged (after Osborn 



34 PARASITES OF THE DOMESTIC ANIIMALS 

from attacking swarms. The most effectual protective measure is the 
shehering of anmials m a cool dark stable during the hours of the day 
when the swarms are most active. 

Treatment. — Animals weakened by the bites may be given a dif- 
fusive stimulant and have the parts locally treated with a solution of 
bicarbonate of soda or ammonia water. 



CHAPTER V 

THE FLIES 

Family III. Tabanidae. — Diptera (p. 23). This family includes 
the so-called horseflies or gadflies. The head and eyes are large, the 
latter often of a brilliant color. The third segment of the antennae has 
four to eight rings. The proboscis of the female is adapted for piercing 
the skin of animals. The males do not attack animals; their mouth 
parts are less powerful than those of the females and are adapted for 
feeding upon the juices of plants. The body has fine hairs; there are no 
bristles. The flight is strong and swift and is accompanied with a 
tormenting buzzing noise. 

The eggs of Tabanidae are deposited in masses upon vegetation grow- 
ing in wet marshy ground. The larvae are carnivorous and are aquatic 
or live in moist earth. 

Tabanus Athatus 

Tabanidae (p. 35). This is the common large black horsefly, having 
a wide distribution in the United States. It is one of the larger species 
of the family, measuring an inch or more in length and havmg a body so 
uniformilv black as to attract attention even when it is upon the wing 
(Fig. 20)." 

The eggs are deposited in masses, usually upon the stems of plants or 
grasses growing in the vicinity of. water. In about seven to ten da3'S 
there is hatched a large cylindrical larva which tapers to a point at both 
ends and has an integument that is somewhat transparent (Fig. 20, a). 
At this stage it lives mostly in moist earth into which it burrows actively, 
feedmg mainly upon worms and the larvae of other insects. While the 
period of larval life is long, in some observed cases lastmg several months 
to a year, the stage of the pupa (Fig. 20, b) is short, the fly emerging from 
its case after a fe^ daj's of pupation. It is probable that the broods are 
carried over the whiter in the larval stage. 

Effect. — The black horsefly is common throughout the summer 
months, attacking cattle and horses usuallj' in the open sunny pasture, 
and inflicting with its long piercing mouth parts a painful womid. For- 
tunately it does not attack in swarms as does the buffalo gnat, nor does 
it instill with its bite as much poison. There is evidence of the severity 
of its wound, however, m the drop of Ijlood which wells up from the seat 
of puncture after the msect has left its victim. While there is little 



36 



PARASITES OF THE DOMESTIC ANIMALS 



after-effect from the Ijites of these flies they are a source of much tor- 
ment to live stock, not only in the jiain produced by their punctures, 
but in their peculiar buzzing, which often terrorizes nervous animals, 

their frantic and heed- 
less efforts to escape not 
infreciuently resulting 
hi injury. 

There can be no 
doubt that the Taba- 
nidiE are concerned in 
the transmission of cer- 
tam blood diseases of 
live stock. It is signif- 
icant as to their possi- 
bilities as carriers of 
anthrax that their at- 
tack seems to be more 
conmionly d ir e c t e d 
agauist cattle than 
horses. 

Protection. — Little 
can be done toward 
repelhng the attacks of the flies. Horses at work are protected in a 
measure by covering them with nets. Where the flies are numerous and 
especiall\- tormentuig it is advisable to remove pasturing animals to a 
well-shaded retreat tluring tlie warmer and sunnier parts of the day. 




Fig. 20. — Tabanus atratus: a, larva; b, pupa; c, adult 
(after Osborn, from Riley. Bui. No. 5, Bureau of Ento- 
mology, Dept. of Agr.). 



Tabanus Lixeola 

Tabanidffi (p. 35).— The Green-head Horsefly (Fig. 21 j. This is the 
most widely distril)uted species in North America. It is about five- 
eighths of an inch in length. Eyes large and bril- 
liant green, abdomen brown, with a conspicuous 
grayish line runnuig longitudinally on its dorsal 
side. It is from this marking that its specific 
name is derived, while the peculiar coloring of the 
cj'es gives to it the common name "Green-head." p ., ^h 

The oval, larval, and pupal stages are passed uneoU '(aftCT Osbora^ 
in moist places, and hi other resj^ects the life cycle from Packard, Bui. No.s, 
is similar to that of Tabanus atratus, though the oepT^of Igo '""'"'"^'^ ' 
larval period is probably not so long. 

The Green-heads appear in especially large aiinubers m marsh.y dis- 
tricts during the brightest and hottest days of the summer. They 
attack in greater numbers than the Black Horseflies, and, especially 




THE FLIES 37 

during warm and surmy weather, their harassing bites cause much 
torture to horses and cattle. They do not fly in cloudy weather, and 
they perish with the frosts of early autumn. 

Family IV. Muscid^ 

Diptera (p. 23). — These flies are small to moderately large, with bodies 
thinly covered with hairs or bare. The bristles of antennae are feathery. 
The abdomen is four-segmented and smooth except for bristles near the 
tip. 

The larvse are apodal maggots, feeding upon decaying animal or veg- 
etable matter. 

MUSCA DOMESTICA 

The common house fly (Fig. 8). Muscidae (p. 37). — The mature in- 
sect is one-fourth to five-sixteenths of an inch in length; dorsal region of 
thorax grayish in color and bearing four longitudinal stripes; abdomen 
yellowish. The mouth parts are trumpet-shaped, adapted for sucking 
up liquids but not for piercing. 

Life History. — In about ten days after emerging from the pupal 
case the female fly seeks suitable material upon which to deposit her 
eggs. This may be anj^ decaying vegetable matter, though usually 
horse stable manure. About one hundred eggs are deposited at each 
laying, of which there are several at intervals of three to five daj^s. In 
eight to twenty-four hours a white, footless larva is hatched. After 
five daj's to one week of feeding and and growing, durmg which period 
it undergoes two molts, the larva enters the pupal stage, the larval skin 
serving as its puparium. Before entering this stage the maggot may 
crawl away from its breeding place and burrow for a short distance 
into the adjacent ground, or find lodgment under a board, stone, or 
dried crust of manure. The stage of pupation lasts from five days to 
one week, and at its termination the adult flj^ emerges. 

According to the longer periods given, the time required for de^'elop- 
ment from the egg to the imago is fifteen days. This time, however, is 
greatly influenced by temperature, under the most favorable conditions 
of which the period for complete metamorphosis may be reduced to ten 
days; a fact always to be reckoned with in dealing with control of the fly 
through the regular and systematic removal of stable mamu'e or other 
material which may serve as its lareedmg bed. 

In the warm midsummer season adult flies may live for six to eight 
weeks, though it is proljable that the average period will not exceed 
thirty days. They may survive the winter in a state of hibernation, 
seeking their retreats in the late fall months, and comuig forth with the 
warm days of early spring to crawl upon the windows as they seek the 
warm sunlight or exit from houses. 



38 PARASITES OF THE DOMESTIC ANIIVLVLS 

Habits and Relation to Disease. — While, so far as known, the 
house fl\' is not an essential host to pathogenic organisms of man and 
the nianimalian domesticated animals, it is, by its structure and filthy 
habits of feedmg, one of the most dangerous of disease-transmitting 
insects. Omniverous in habit, it will feed upon decaying vegetable and 
putrid animal matter, excrement, vomit, sputum, or other revoltingly 
filthy material. Direct from such sources of infection it may pass to 
the food upon our tallies to which it is equally attracted, leaving a 
trail of contamination wherever it may drag its filthy parts. 

From the viewpoint of the bacteriologist it would seem superfluous to 
discuss the house fly as a carrier of disease-producing bacteria. The 
form of its proboscis, habit of regurgitating its food, its six bristly feet 
(Fig. 8), each terminated by a sponge-like structure secretijig a sticky 
substance, together with the vile material which it visits, make it both 
by stnu'ture and habit an ideal transmitter of such infectious diseases as 
typhoid fever, dysenter^•, cholera, glanders, anthrax, and ophthalmia. 
Furthermore, positive evidence of the degree to which this insect is a 
canier of bacteria has been well set forth by laboratory experiment. 

Control. — As a widely disseminated menace to public health the 
house fly jjresents a problem that can only be successfully dealt with by 
comnuuiity action. The measures taken should look to control rather 
than elimination, the latter, however desirable, being scarcely possible 
under present conditions. While it prefers horse manure, it is known 
that almost any fermenting material will serve as a breeding place, and 
it therefore follows that, in oider to successfully combat this pest through 
its sources of piopagation, all such material nuist be systematically re- 
moved, screened off. or so treated as to I'ender it unsuitable for the 
development of the larvae. Manure should be removed at least once a 
week, and if possible at once spread upon the fields. Kitchen garbage 
should be likewise removed, and in the meantime kept in tightly closed 
receptacles. Access of flies to the vaults of outhouses can be prevented 
by their proper structure and screenmg. 

Protection. — As to measures of protection to the household against 
flies, there is little to be said that is not of connnon knowledge. The 
first of these to be mentioned is the thorough screenuig of doors and 
■ivindows. Kitchens being especially attractive to flies, they should be 
doubly ])rotected by screening the back ])orch, the screen doors at these 
locations liemg well fittuig and made to withstand theii- freciuent use. 
Flies that have gained entrance are best gotten rid of by burning pyre- 
thi-um ])owder. A good method for the treatment of a room is to sprinkle 
the powder uj^on a hot shovel after first closing the doors and windows; 
if the kitchen, the powder may be sj^rinkled over the stove. It is best 
applied at night, leaving the room tightly closed. In the morning the 
flies w-ill be found lying about dead or stupefied, when they may he 



THE FLIES 39 

swept up and burned. The use of poisonous liquids set around in dishes 
has but little efhcacj^ and for other reasons is not to be recommended. 
Sticky fly paper, to be most effectual, should be placed in parts of the 
room where there is most sunlight, as in the vicinity of wmdows. 

In this connection it should be borne in mind that adult house flies 
and their allies seek the light, while their larvse avoid it, characteristics 
referred to in the first case as light positive and in the second as light 
negative. This habit as to light is to be reckoned with and taken ad- 
vantage of in measures looking to fly control. 

Stomoxys Calcitrans 

Stromoxys stabulans. Stable fly; stinging flj^ Muscidse (p. 37). 
About the size of the house fly. The color is brownish gray; proboscis 
black, slender, bent near its base, and extendmg forward from the head, 
fitted for piercing. The thorax bears four longi- 
tudinal stripes which may be more or less broken. 
The abdomen is stout, grayish, and spotted dor- 
sally. The wings hyalme, and when at rest widely 
spread apart at the tips. The fly rests with its 
head well elevated and with wings slopmg later- 
ally downward and outward (Fig. 22). 

The eggs are about one mm. in length, curved 

''?, ,, -J. -J f ■ u^ 1 Fig. 22.— Stomoxys cal- 

on one side, on the opposite side straight and citrans, enlarged. 
grooved. The larvse resemble those of the house 

fly. They may be differentiated by the posterior stigmal plates, 
which in the larvse of the house fly are large, irregularly oval, and close 
together, while in Stomoxys they are smaller, round or triangular, and 
much farther apart. 

Life History. — The life-cycle of the stable fly is considerably longer 
than that of the house fly; like the latter it breeds in horse manure, but 
not to the same extent. Manure well mixed with straw is that most 
sought. Ideal for the deposition of its eggs are damp and fermenting 
collections of such material as cut grass, alfalfa, hay, grain, or piles of 
weeds. The eggs are deposited deep into the fermentmg mass, and, 
under favorable conditions of temperature, will incubate m about three 
days. The larvse are active feeders and complete their growth in from 
twelve to thirty days. As in related flies, the puparium is formed by 
the hardenmg of the last larval skin. The dui'ation of the pupal stage 
will again vaiy according to weather, lasting from six to twenty days, or, 
if cool, it may he much longer. About twelve days may be taken as an 
average period. The time required for complete development may 
accordingly be set down as from twenty-five to thirty' da>-s under 
ordinarily favoral^le conditions. It is probable that the species is car- 
ried over the winter months in our Northern States in the larval and 




40 PARASITES OF THE DOMESTIC ANIjVL\LS 

pupal stages. Development with the appearance of adult flies will 
occur in warm staliles during this season. 

Occurrence and Effect. — The stable fl.y is of world-wide distribution, 
and is conunonly mistaken for the house fl}^, the term "bitmg house 
fly" being often ajiplied to it from its habit of entering our houses during 
damp, ramy weather and in the cooler days of early autumn. It may 
quickly be distinguished from the common house fly, however, by its 
elevated head when at rest, its protruding, bayonet-like proboscis, and 
its wings, which are widely spread apart at the tips. 

Though commonly called the stable fly, Stomoxys is found in far less 
numbci's about stables than is the house fly, and, as it will not visit such 
filth as does the latter, it is not such an offender against the cleanliness 
of dairy and other food products. Both sexes of Stomoxys, however, 
are vicious blood-suckers, and their bite is especially a source of torture 
to thin-skinned, sensitive animals. Typically an out-of-door fly, it is 
most likely to enter stables in the cooler days of late summer or earlj^ 
autumn when it will attack horses and cattle, attaching itself bj^ prefer- 
ence upon the legs. Their sharp sting is manifested by the stamping, 
kicking, and general restlessness of the victims. The punctures are 
often followed by the formation of papules which may coalesce and 
rupture, leaving a scaly, more or less thickened skin with hairs scant, 
lusterless, and erect. To the daily they are a source of loss in milk 
production through the worry and imrest caused by their attacks. 

Relation to Disease. — The possibilities of the stomoxys fly as a 
di.sseniinator of infectious diseases have in recent years received con- 
siderable attention. Its habit of visiting a number of hosts before 
becoming engorged with lilood, together with its deep puncture, war- 
rants us in charging against this species possibilities in the transmission 
of anthrax in cattle and glanders in horses. By some authors it is re- 
garded as a carrier of the trypanosome {Trypanosoma evansi) which 
produces surra of honses. Of this, however, there is no conclusive experi- 
mental evidence. As to the responsibility of the stable fly for the spread 
of infantile paralysis, it will be sufficient here to quote Riley and Johann- 
sen, who. after reviewing the evidence, thus state their conclusions 
(1915): "The evidence at hand to date indicates that acute anterior 
poliomyelitis, or infantile paralysis, is transmitted by contact with 
infected persons. Under certain conditions insects may be agents in 
spreading the disease, but their role is a subordinate one." 

Control. — Control measures consist in removing materials which 
aft'ord favorable breeding places for the fly. Collections of moist and 
fermenting feed material, such as have been mentioned, should be re- 
moved and scattered in a layer suflficiently thin to insure thorough 
drying. It will then be unsuitable for the development of stomoxys 
larvae, as they require considerable moisture. Manure in which there is 



THE FLIES 41 

mixed considerable straw affords a favorable medium for the propaga- 
tion of this fly, — a further reason for its systematic removal to be at once 
spread upon the fields, as stated in control measures for the house fly. 
It should be borne in mind, however, that stables are not predominant as 
breeding places of the fly under consideration, as is the case with the 
house fly. Stomoxys is attracted to stables because the animals from 
which it obtains its meal of blood are contained there. The favorite 
material for the deposition of its eggs is likely to be found elsewhere. 
These flies like the open, and districts far from stables may be overridden 
with them. 

Protection. — Little can be done in the way of direct protection of 
live stock against the attacks of stable flies beyond thorough screening, 
the effectiveness of which is much lessened by the frequent opening of 
doors customary about stables. Means of keeping them out should be 
especially looked to in cloudy, damp weather, and in the cool mornings 
of early autumn, at which times they are most likely to seek the interior 
of stables and houses. 

Lyperosia Ieritans 

Hcematobia serrata. — The horn fly (Fig. 23). Muscidse (p. 37). About 
half as large as the house fly and like it in shape and color. The mouth 
parts are adapted for piercing and sucking blood, but differ from those 
of the stable fly in that the palpi are almost as long as the proboscis and 
are slightly spatulate. 

The eggs (Fig. 23, a) are about L25 mm. in length, irregularly oval, and 
reddish brown in color. They are deposited in the fresh dung of cattle, 
and, under favorable conditions of temperature, will hatch in about 
twenty-four hours. 

Life History. — Newly hatched larvae are about 2.5 mm. in length, 
and pure white. When full grown they are about 7 mm. in length and 
somewhat darker m color. The larvae burrow into the dung and reach 
their full growth m about four days (Fig. 23, b). When ready to trans- 
form into the pupal stage the larvae descend into the dryer parts of the 
dung, or for a short distance into the gromid beneath it. The puparium 
(Fig. 23, c) is about 4.5 mm. in length, irregularly ellipsoidal, and dark 
l)rown m color. The pupal stage occupies from five to ten days, therefore 
the time for full development from the deposition of the eggs will be, 
according to the above, from ten to fifteen days. 

Occurrence and Habits. — The horn fly is an importation from 
Europe, making its first appearance in the vicmity of Philadelphia about 
the year 1886. It was first noticed as a pest to cattle in this country in 
1887, from which time it has spread rapidly and at present is found in 
practically all parts of the L^iiited States and the greater part of Canaila. 

The popular name "horn fly" is derived from the habit peculiar to 



42 



PARASITES OF THE DOMESTIC ANIMALS 



this species of clustering about the base of the horn, though this only 
occurs when they are cjuite abundant. Their purpose in collecting here 
seems to be for rest in a location where they are not liable to be dis- 
turbed. There is a somewhat prevalent belief that the flies damage the 
horn liy eating into it, depositing eggs, and developing maggots which 
ma>' penetrate to deejier structures, etc. This is a popular error for 
whicli there is no foundation, for, beyond "fl.y specking," it has not been 
observed that the flies do any injury to the horn. 

Field study will show that this insect assumes two characteristic posi- 
tions. In the resting position, as they are found when ujion the horns. 




Fig. 23. — Lypcrosia irritans: a, egg; f), larva; c, piiparium; d, adult in biting 
position — all enlarged (after Osborn. from Riley and Howard, Bui. No. 5, Bu- 
reau of Entomology, Dept. of Agr.). 

the wings are held ncarl.v flat down the liack, overlapping at their bases 
and moderately diverging at their tips. The proboscis is extended for- 
ward, and the legs are not widely spread. When active and feeding, on 
the other hand, the wings are slightly' elevated and held almost at right 
angles to the body, while the legs are spread. The proboscis is nearly 
perpendicular in position, and penetrates the skin of the animal at- 
tacked. To secure this position it works its way to the skin, and is 
usually observed more or less covered by the hairs. In damp, rainy 
weatiier they may be noticed as particularly abundant beneath the 
hairs of the ventral surface of the body. 

Efifect. — Horn flies appear early in May and become most abundant 
in July and August. With the coming of cold weather they disappear, 



THE FLIES 43 

their full period depending upon season and latitude. During the time 
of their activitj'^ they are a veritable pest to cattle, causing interference 
with their grazing and disturbance of their rest, with consecfuent un- 
thrift and serious loss in productiveness. Horses do not escape their 
annoyance, but cattle seem to be the special object of their attack. 
Though the damage done is chiefly through their torment, the con- 
siderable amount of blood extracted from the animal by the large 
swarms which feed upon it must seriously contribute to the weakening 
effects. Further, as in all blood-sucking Diptera visiting cattle, we are 
justified in inferring that this fly may be a transmitter of infectious blood 
diseases, such as anthrax, though as to this there has as yet been little 
if any investigation. 

Control. — In control measures two lines of procedure should be fol- 
lowed, one looking to prevention of multiplication, the other directly 
protecting cattle from attack. Of these the former is most effective and 
involves such treatment of breeding places as will prevent larval develop- 
ment. As eggs are deposited in fresh dung, which must remain moist for 
the proper nourishment of the hatched larvse, any treatment of the 
droppings which will cause them to rapidly dry out will prevent or 
greatly inhibit larval development. Scattering or thinly spreading this 
manure, as may be done by a rake or by drawing brush across the fields, 
will accomplish this; the latter method, more economical in time and 
labor, is best adapted for large pasture areas. Hogs ruiming with cattle 
will serve to scatter the manure to a large extent. The use of lime, which 
may be applied by simply throwing it over the droppings in the pasture, 
is very effective in destroying the larvse. While piles of cow manure, 
especially those containing considerable straw, afford good breeding 
places for the stable fly, the horn fly will not seek this material to any 
great extent for the deposition of its eggs. 

Protection. — For the direct protection of cattle a number of oleagin- 
nous repellents are reconmiended. A mixture of fish oil and tar, equal 
parts, applied to the regions most attacked, is one in general use. Almost 
any oily or greasy substance is of value, though causing the animal to 
become somewhat unsightly from adhering collections of dust and dirt. 
Sprays of kerosene emulsion (page 48) may be used with advantage, 
though the effectiveness of such treatment is very transient. The 
followmg mixture is reconunended by the Kansas Experiment Station: 
resin (]3ulverized), one part; shaved so^p, one part; water, one-half part; 
fish oil, one part; oil of tar, one part; kerosene, one part; water, three 
parts. The resin, soap, fish oil, and one-half part water are l^oiled to- 
gether imtil the resin is dissolved, then the three parts water are added, 
and finally the kerosene and oil of tar. The mixture should be thor- 
oughly stirred and laoiled for fifteen minutes. This preparation when 
cool and applied as a spraj- will act as an effective repellent for twenty- 



44 



PARASITES OF THE DOMESTIC ANIMALS 



four to forty-eight hours. It is necessary, therefore, to regularly repeat 
the application if the animals are to be continuously protected. Re- 
pelling agents are best applied in the evening when cattle are stabled or 
yarded. 

Tsetse Flies 

Genus Glossina. — Mu^cidsB (p. 37). The tsetse flie? (Fig. 24)Jare 
about the size of liouse flies, or may be somewhat larger. ] The general 
color is Hght lirown. When at rest the proboscis pi'ojccts in frontjof the 
head. At the base of the proboscis is a bulbous enlargement, arista 




Fig. 24.— Tsetse fly. 

])lunio8e above. The resting wings are folded scissors-like over the back. 

'J'hcsc flics are found only m certam areas m Africa. 

Glossina Palpalis. — Glossina (p. 44). This species is 8 to 9 mm. 
(5; 1(3 to 3/8 of an inch) in length. The color is brown dusted with gray. 
The antenna are black. All segments in the hind tarsi are black. The 
fourth and fiftli segments of the fore tarsi are black. The halteres are 
white. 

Glossina Morsitans. — Glossina (p. 44). About the same size and 
color as (1. jKiIixiIi.'i. The antennae are dark. The first three segments 
of the hijul tarsi are yellow, the fourth and fifth segments black. The 
foiu'th and fiftli segments of the first and second pairs of tarsi are black. 

Glossina lom/ipalpis is a species which in characteristics and distrilju- 
tion is almost identical with G. morsitans. 

Breeding Habits and Habitat. — The (Jlossina deposit hatched larvae 
among inots of tropical vegetation. When deposited the larvae are well 



THE FLIES 45 

advanced and within a few hours enter upon the pupal stage which re- 
quires from six to eight weeks. Occurring only in Africa, they are most 
abundant in heavily wooded districts penetrated by water courses. 
Both sexes are blood-sucking, and it is in such locations that they are 
most likely to find the wild animals upon which they feed. 

Relationship to Trypanosomiasis. — As transmitters of trypanoso- 
miasis to man and domestic animals, tsetse flies may be regarded as the 
world's most dangerous insects. The first observation of trypanosomes 
in the blood of mammals was made by Lewis, who in 1877 described a 
trypanosonie {Trypanosoma lewisi) of the blood of a rat. Three years 
later another trypanosonie (T. evansi) was studied as the cause of surra 
in horses. When Bruce in 1894 demonstrated the relationship between 
tsetse fly disease of horses in Africa, the cause of which was unknown, 
and nagana, trypanosomes received much more attention as to their 
pathogenic importance. The further investigations of Bruce as to the 
part plaj^ed by the tsetse fly in the transmission of this disease are best 
given in his own account, from which the following is an excerpt: 

"When it was once established that the two diseases were the same, 
experiments were made to find out how the animals became mfected, 
whether the fly was the carrier or the mere concomitant of the low-lj^ing, 
unhealthy district, and, if a carrier, if it was the only carrier of the disease 
from sick to healthy animals. Horses taken down into the fly country, 
and not allowed to feed or drink there, took the disease. Bmidles of 
grass and supplies of water, brought from the most deadly parts of the 
fly comitry to the top of LTbombo and there used for fodder for healthy 
horses failed to convey the disease. Tsetse flies caught in the low countiy 
and kept in cages on top of the mountain, when fed on affected animals, 
were capable of givmg rise to the disease in healthy animals up to forty- 
eight hours after feeding. Tsetse flies l^rought up from the low comitry 
and placed straight way upon healthy animals were also found to give 
rise to the disease. The flies were never found to retain the power of 
infection for more than forty-eight hours after they had fed upon a sick 
animal, so that if wild tsetse flies were brought up from the low countiy, 
kept without food for three days, and then fed on a healthy dog, the}' 
never gave rise to the disease. Li this way it was proved that the tsetse 
fly, and it alone, was the carrier of nagana. Then the question arose as 
to where the tsetse flies obtained the trypanosomes. The flies lived 
among the wild animals, such as buff'aloes, koodoos, and other species of 
antelopes, and naturally fed on them. It seemed that, ui all probability, 
the reservoir of the disease was to be found in the wild animals. There- 
fore, all the different species of wild animals obtamable were examined 
both by the injection of their blood into healthy susceptible animals, 
and also by direct microscopic examination of the blood itself. In this 
wa-s' it was discovered that manv of the wild animals harbored this 



46 PARASITES OF THE DOMESTIC ANi:\IALS 

tryiianosoine iii their l:)lo(xl. The parasites were never numerous, so 
that it was only after a long search that they could be discovered by the 
microscope alone. The wild animals did not seem to be affected by the 
trypanosomes m any way; they showed no signs or sjanptoms of the 
disease, and it, therefore, appeared probable that the trv'panosomes lived 
in their blood as harmless guests, just as the trypanosome of the rat lives 
in the blood of that animal." 

As Trypanosoma brucei is now known to be the organism causing the 
fatal nagana of horses and nniles of Africa, so T. gambiense is known to 
be the cause of sleeping sickness of man. The relationship of the tsetse 
fly to human trypanosomiasis was shown in a way very similar to that 
by which Bnace reached his conclusions. While the tsetse species 
Glossina niorsilans and G. longipalpis are especially concerned in the 
transmission of nagana. and G. palpalis likewise related to sleeping sick- 
ness, it has been shown by students in the field of protozoology that not 
only biting flies, but mo.squitoes, lice, and leeches may carry trypano- 
somes fi'om one vertebrate host to another. 

E.\pei'iinent has shown that the trypanosomes adhering to the pro- 
boscis of the biting fly after it has fed upon the blood of an infected 
animal rapidly lose their vitality, becoming sufficiently attenuated 
within fort\--eight hours to be noninfective. The fly, therefore, can 
only inoculate meclianically, that is by the puncture of its soiled pro- 
boscis, within a few hours after it has become a carrier of the infecting 
organism. It is now known, however, that trypanosomes taken into 
the stomach of the fly with its meal of blood pass through a metamor- 
phosis involving sexual forms, and that at the end of about twenty-eight 
days the fly may again become infectiv^e. At this time the parasites 
have reached the salivary glands and here they remain during the re- 
mainder of the life of the fly. How long such a fly may retain its power 
to infect is yet a question, though it has been found by the Sleeping 
Sickness C'onnnission to be at least three months. The duration of the 
life of the tsetse fly has only been observed upon specimens in captivity, 
but it is probable that it is about four to .six months. 

Control. — Measures looking to the control of the breeding of the 
flies are limited practically to exclusion owing to the fact that the larval 
period is passed withhi the body of the female, hence offers no opportu- 
nity for attack through sources of larval food supply. The fact that 
tsetse flies seek the vicinity of water courses surrounded by wooded 
areas may be taken advantage of in excluding them from locations of 
settlement. With a view to this it has been reconunended that clearings 
be made over an area of six hundred to eight hundred >'ards at some 
distance from streams of water, the water supply being obtained from 
wells. The difficulties presented, however, in the control of the fly are 
numerous and in manv features seem un.surmountable. The ultimate 



THE FLIES 



47 



solution of the problem probably lies in immunization against the 
tsetse fly diseases, as to which little progress has yet been made. 



Family V. Hippoboscid^ 

Diptera (p. 23). — The body is flattened. Wings are present or absent. 
The wmg veins are crowded toward the anterior margin. The head is 
sunk into an emargination of the thorax; the antennse inserted in pits 
near mouth; mouth parts adapted for piercing and sucking blood. 
The legs are stout, termuiated by strong claws. The abdomen is large 
and sacular with segments indistmct. 

The Hippoboscidse are pupiparous, the eggs being hatched and 
nearly the whole of the larval stage passed within the body of the parent. 
The larvae are extruded only when nearly ready to transform into pupae. 

All are parasitic upon birds and mammals. Hippobosca equina is a 
winged species occurring upon the horse, and known in England as the 
forest fly. 

Melophagus Ovinus 

The sheep "tick." — Hippoboscidse (p. 47). Three-sixteenths to one- 
quarter of an inch in length. The color reddish or grayish brown. 
The wings and halteres are ab- 
sent. The head is small and 
sunken into the thorax; ab- 
domen large, sac-like, and 
covered with short spines 
(Fig. 25). 

Life History. — Matured lar- 
vae are extruded from the body 
of the female and at once enter 
upon their pupation, the red- 
dish brown pupae adhering to 
the wool fibers. The pupal 
stage occupies three to six 
weeks according to season and 
temperature, the shorter period 
occurring durmg the summer. 
At sexual maturitj^ the deposi- 
tion of pupae begins, each fe- 
male depositing from eight to 
ten. Probably the hfe of the 
tick will not exceed four to five 
months. 

Occurrence. — The sheep tick is distritnited over all parts of the 
world where sheep are kept. Its parasitism is continuous, the pupiparous 





..^^ji*^^ 


'»VV . 


Jtek. 


t 


i 




y 


a 




.'I 


^ 




^ 


\ 


rm 


w 


EK j 


^ 


^ 

" 


^^ 


r 






■'• 'n 







Fig. 25. — Melopliagus ovinus (from 
graph of mounted specimen, by Hoedt). 



photo- 



48 PARASITES OF THE DOMESTIC ANII\L\LS 

habit of bringing forth its young adapting it to spend its whole Hfe upon 
the host from which it never migrates imless to attach to another animal 
of the same species. It is probable that this migration occurs principally 
at the time of shearuig when the ticks leave the sheared sheep and crawl 
upon the lambs. Off the host the ticks will not survive longer than a 
few days, proliabl\' all will be dead within a week. 

Effect. — All Ijreeds of sheep are alike subject to attack, the presence 
of the "tick," or "louse," as it is commonly called, and the injur.y which 
it causes, being a matter of common knowledge to sheep breeders. Sheep 
are not materially affected by a few, but if in larger numbers, their 
presence will be manifested by rubbing, scratching, and biting at the 
fleece. Loss of flesh and general unthriftiness will occur in badly in- 
fested animals. Where the ticks are jjrevalent lambs may be attacked 
by large mmibers at shearing time, in which condition many will die 
unless jiromptly relieved. 

Treatment. — In the winter months, when the long wool will not 
permit of other treatment, the ticks may be greatly reduced in number 
b.y the use of iiyrethrum powder which should be freely blown deep into 
and upon the fleece over all parts of the body. The most effectual treat- 
ment is best applied after shearing and consists of the apjilication by 
dipping or as a wash of such remedies as creolin, zenolium, lysol, or 
cresol, used in two to three per cent, strength. Decoction of tobacco, 
in strength of three to four per cent, is also used, but, to avoid danger of 
nicotine* poisoning, should not be applied to all parts of the body at once. 
Kerosene emulsion, which has a wide range of usefulness in the treat- 
ment of external parasites, is another of the numerous dips resorted to 
in this connection. The enuilsion may be made either with milk or .soap 
according to the following formulae: 

Milk emuhion.- — To one part milk add two parts kerosene and churn 
by a force pump or by other means of agitation. Dilute the resulting 
emulsion with eight to ten times its bulk of water. 

.Soap emulsion. — Dissolve one-half a pound of hard soap in one gallon 
of hot water and, while still at near boiling jjoint, add two gallons of 
kerosene. Emulsify by use of force pump or other means of agitation. 
Dilute one part emulsion with eight or ten parts water. 

These enuilsions may be used in the jjroiiortions given as a spray, 
wash, or dip. 

None of these dips will kill the pupie, and, therefore, keeping in 
mind the life history of the parasite, the treatment should be re- 
peated in about twenty-four days. If the dipping has lieen done in 
the cooler weather of autumn, this interval should be accordingly 
pi'olonged. 

As the movement of the ticks from the sheep to the lambs takes place 
principally at the time of shearing when the insects are removed from 



THE FLIES 49 

their host with the fleece, it is well at this time to keep the lambs at 
some distance from the stored wool. This precaution should be ob- 
served for at least a week from the time of shearing, at the termination 
of which period the ticks which have been removed with the wool will 
be dead. 



CHAPTER VI 

DIPTEROUS LARY.E 

Flesh flies, blowflies, botflies. — The larvse of these flies produce a 
form of parasitism to which the term mj'asis (also mj-iasis, and myiosis) 
is applied. Various forms of myasis are recognized according to the 
location of the larvae, as cutaneous, muscular, nasal, gastric, and intes- 
tinal. AVith certain species, as those of the family CEstridse, or true 
botflies, the larval parasitism is obligate upon or within a living host 
animal, while the larvfe of the flesh and lilowflies of the family Muscidse 
may attack either living or dead, usually decomposing, tissue. 

Chrysomyia Macellaria 

Compsomyia macellaria; Cochlioniyia macellaria, Screw worm fly. — 
^luscidae (p. 37). Three-eighths to half an inch in length; color bluish 
green with metallic reflections. There are three longitudinal black 
stripes \ipon the thorax. The head is reddish or yellowish brown; 
thorax and abdomen covered with stiff black hairs (Fig. 26). 

The eggs are about 1 mm. in length, white and cylindrical. They 
are deposited in masses of three hundred to four hundred upon dead 
and deca>'ing flesh and upon woiuids, sores, or within the nostrils or 
other natural mucous openings of man and lower animals. Hatchmg 
may occur in from one to twelve hours from the time the eggs are 
deposited. 

The larvae are white, apodal, slender, and cuiite active. The head 
and segments are provided with spines which facilitate their burrowing 
into the living or putrefying flesh upon which they feed, a habit which 
gives to the mature insect its connnon name of screw worm fly. Under 
most favorable conditions the full larval growth is reached in three days, 
at which time they maj- be half an inch or more in length. When mature 
the.\' leave the flesh upon which the>' have been feeding and bury them- 
selves in the earth near by, in which location they enter upon pupation. 

The pupa> are 6 to 9 nun. in length, somewhat barrel-shaped, and 
dark Iirown in color. The pupal stage may last from six to twelve days. 

Occurrence and Effect. — The screw worm fly is widely distributed, 
being found throughout North and South America. In the United 
States it is especially abundant hi the South, where it is responsible for 
the most serious cases of human m^'asis occurring in this comitiy. It 
begins to attack in June, l)ut has its greatest period of activity in the 



DIPTEROUS LARV^ 



51 



three months which follow. In its attacks upon man it usually deposits 
its eggs in the nostrils or mouth while the indi\'idual is sleeping. It is 
especially attracted if the parts are rmclean, as from the discharge of 
nasal catarrh or collections of vomit about the lips. Persons in a drunken 
stupor are especially liable to attack. For the same reason open sores 
contammated by collections of pus or blood are equally attractive to it. 

The flj''s greatest injury as a pest to domestic animals in the United 
States occurs in the Southwest, where cattle are the greatest sufferers 
from its ravages. In these animals the flies are attracted to wounds of 
operations, such as dehorning, branding, castrating, etc., and to injuries 
such as may result from hooking or 
barbed wire. In fact any open 
womid or exposed mucous mem- 
brane, especially if soiled with an 
odorous discharge, is a favorite seat 
of attack. 

Upon hatchmg, the larvse at once 
proceed to attack the tissues and 
may rapidly produce a serious de- 
struction and mutilation. They grow 
rapidly as thej^ consume the tissues 
adjacent to them, and iir locations, 
as parts of the limbs where there is 
little fleshy covering, the bones may 
be laid bare. 

Protection. — As most of the fatal tp .^n n n ■ 

hiG. 26. — (_.ompsom^^a macellaria — en- 
cases of myasis m man from this larged (after Osborn, from Francis, Bui. 
cause are due to deposition of eggs ^o. 5, Bureau of Entomology, U. S. Dept. 

in the nostrils while the person is ° ' ^'^ 

.sleeping, the first measure of precaution is to protect from attack by the 
use of netting. Those sleeping out of doors in infested regions are most 
exposed, but sleepmg rooms should also be thoroughh' screened. Open 
sores and wounds should of course be kept free from collecting discharge 
and covered with clean, dry dressmg. The same precautions as to 
cleanliness of wounds and exposed mucous membranes applies to domes- 
tic animals. The vulvae of cows recently fresh, especially if there has 
been a retention of the placenta, and the navels of calves offer fa^•orite 
pomts for attack and should particularly be guarded. 

Treatment. — Where sores and exposed mucous memliranes have 
already' become infested with worms a disinfecting wash, such as a one 
to three per cent, solution of carbolic acid, should be used. For injection 
into regions where the maggots have penetrated, the injection of carliolic 
acid or creolin in alioiit five per cent, strength will destroy worms witli 
which it comes in contact. Chloroform diluted to a strength of about 





52 PARASITES OF THE DOMESTIC ANIMALS 

twenty per cent, is also recommended for this purpose. An ordinary 
machinist's oiler affords a practical method of applying such agents. It 
has the advantage of deep application without waste of the material. 
For deeply infested womids a final packing of oakum and oil of tar should 
be apjDlied, and this should be covered by a protective dressing of tar 
and oakum as a prevention from further attack. 

Sarcophaga Sarracenle 

A flesh fl\-. — Muscidffi (p. 37). In markings somewhat similar to the 
house fly, but considerably larger. The general color is light gray; eyes 
reddish brown. Body spLiiy. 

The female deposits larvae upon fresh meat, or in the wounds of living 
animals. Under favorable conditions the larval stage is completed in 

about six days. The 
^.d<f^> ,. <^bi-^ari^ /^^Bfek^ mature larvae crawl to 

a convenient shelter 

where they undergo a 

,, ,- ., . I ■ f .1 fl 1 fl /c 1 % pupation from which 

]'ii:. li. — MctamorphusLS of the Iipsh fly (barcophaga) : ' ' . . 

a, eggsib , young Iar\ie just hatched; c, d, full-grown larva"; the adults ISSUC m from 

e, pupa; f, imago (after Orton, by Dodge; Copyright, 1894, twelve tO fourteen 

by Harper <t Brothers). , ,^. f,-^. 

days (iig. 27). 

Protection. — The flesh flies are of world-wide distribution, and are 
of most importance as they affect fresh meats in the household or meats 
in storage. As a protection in such cases the flies should be screened off 
at some distance, as larvae which have been deposited in the vicinity of 
meat will crawl to it, though it may not be accessible to the flies. 

To prevent their attack upon wounds, the same general procedure 
may be adopted as recommended for the preceding species. 

Calliphora Vomitoria 

Blowfly. — Muscidae (p. 37). Somewhat larger than house fly; eyes 
brownish in color; abdomen l:)luish green with metalic lu.ster and usually 
pollinose. 

The eggs are oval, white in color, and are deposited upon decomposing 
animal and vegetable matter and in wounds of animals. Hatching may 
occvu' in from a few hours to one or two days, the shorter periods occurring 
in hot weather. After from three to nine days of feeding, the matured 
larvae seek the ground, become buried for a short distance, and in this 
location enter upon their stage of pupation. The time required for the 
entire life cj^cle, including a prepupal period of several days, may be 
from two to five weeks, depending greatly upon temperature. Under 
ordinary' conditions it would pi-obably occupj' about three weeks. 

The blowflj- agrees with the flesh fly in its habits, with the exception 



DIPTEROUS LARV^ 53 

that it deposits eggs instead of living larvae. After hatching the manner 
of attack and the effect upon infested meat and wounds is much the 
same and calls for the same treatment. 

Family VI. CEstrid^ 

Diptera (p. 23). Botflies, warble flies. The head is large, bearing two 
faceted eyes widely separated, antennae short and sunken into pits in 
the front of the head. The mouth parts are rudimentary, most all of the 
flies living in the adult stage without food. The body is heavy and 
somewhat hairy. The coloration is usually inconspicuous. 

The larvae are thick and twelve-segmented, the first two segments 
not always distinctly separated. There is no demarcation into body 
regions, only a cephalic and anal end can be distinguished. The body- 
segments are frequently provided with rows of spines. Buccal hooks 
may or may not be present. Tracheal openings are at the posterior 
extremity. 

The larvae are parasitic in the stomach and intestines, mucous mem- 
branes, subcutaneous connective tissue, nasal passages, and sinuses of 
facial bones of mammals ; other parts are also invaded by their migrations. 
When completely developed the larvae leave these locations in the host 
and pass to the ground where they enter the pupal stage. 

The flies of the family CEstridae are of world-wide distribution. 

Gastrophilus intestinalis {G. equi). CEstridae (p. 53). The horse 
botfly (Fig. 28, h). The body of the female is one-half to flve-eighths of 
an inch in length and is very hairy. The head, thorax a;nd abdomen are 
brown. The wings are transparent with dark spots, those near the center 
passing entirely across the wing transversely. The abdomen is rather 
long and tapers to a point. In the males, which are rarely seen, the 
abdomen is light brown or yellow, "and it is not tapering. In other re- 
spects the males closely resemble the females. 

The larvae (Fig. 28, c, d and g) when full grown are about three- 
fourths of an inch in length. At the head extremity are two buccal 
hooks by which attachment is made to the gastric mucosa (Fig. 28, e). 
The body-segments are bordered by short spines (Fig. 28, d). 

Habits. — Like other members of the (Tstridae, the horse botfly at 
maturity is extremely active, flying chiefly during the warmest and 
brightest days of the summer, and generally frequenting pastures ia 
the vicinity of woods. It is the habit of the female to hover near the 
horse with its long, pointed abdomen bent downward and forward. The 
fly then darts toward the horse, deposits its egg, retreats, and again 
hovers initil ready to repeat the operation. The eggs (Fig. 28, a and b) 
are yellow in color, about one-sixteenth of an inch in length, and tapermg 
toward the attached end, the free end being provided with an operculum 
which is set obliquely and gives to this end somewhat of an obliquely 



54 



PARASITES OF THE DOMESTIC ANENIALS 



cut off appearance. They are generally deposited upon the hairs of the 
antci'ior parts of the body, as upon the forelegs, breast, shoulders, and 
under side of the bodj', regions which are most readily reached by the 
lips of the horse. It is not uncommon, however, for eggs to be attached 
to the sides of the neck, lower jaw, cheeks, mane, and other parts, the 
lar\:e in such cases reachuig the mouths of horses by their licking or 
nipping at each other. 

Life History. — The eggs are deposited rapidlj^ with their free ends 
down, and adhere to the hairs by a viscid substance which quickly dries 




Fig. 28 — -Gastrophilus intestimilis: a, egg — eolarged; b, egg — natural size; c, young larva; 
d, young larva — much enlarged, showing spiny armature; e, oral hooks; f, body spines; g, 
full-grown larva — twice natural size; h, adult female (after Osborn, Bui. No. 5, Bureau of 
Entomology, U. S. Dept. of Agr.). 

and gives them a firm attachment. At this tune they contain lar\-se 
which have undergone a more or less advanced development. 

Observations upon the botflies duruig recent j-ears have been some- 
what disturbuig to conclusions formerly held and apparently necessitate 
a certain revision of the life histories which have generally been given for 
them. Accordmg to the observations of Roubaud (1917) upon Gas- 
trophilus intestinalis, the eggs of the fly do not open spontaneously, and 
the larvaj may not escape from them for several weeks. The opening 
of the operculum and freeing of the larva probably occurs when the 
horse rubs an itching or irritated area with his nose or bites it with his 
teeth, the horse rarely Ucking itself. By experunents with bot larvae on 
guinea-pigs Roubaud demonstrated that when the hatched larva is 
brought in contact with the buccal mucosa it at once burrows into this 
membrane and lies parallel to its surface. In two or three days it dis- 
appears, but he notes that one was seen traveling along the side of the 



DIPTEROUS LARViE 55 

tongue for nine days, during whicii time it grew to three times its first 
dimensions. Before leaving the buccal mucosa the larvae probablj' 
imdergo a molt and then proceed to the stomach. These observations 
indicate that the larvae of the botfly escape from the eggs when the horse 
bites at his skin or rubs it with his lips, and that thej" burrow into the 
buccal mucosa where they undergo a degree of development before 
passing to the stomach. 

Within the stomach cavity the larva fixes itself to the walls b^^ its 
buccal hooks. Later the head becomes deeply inserted into an alveolus 
which is formed mrder the influence of the irritation to the mucosa. In 
this position the larva feeds upon the tissue juices and the products of 
the irritation which it sets up, becoming fullj'' grown in about ten months. 
The period of larval development usually terminates from May to 
August, more especiall}' in Jmie, due to the fact that the deposition of the 
eggs occurs most actively in the month of August. At this time the 
larva becomes detached from the gastric mucosa, passes to the intestines, 
and with the intestinal contents leaves the body of its host. 

The change into the pupal stage is made either in the horse manure 
or after the larva has burrowed for a short distance into the ground. 
At the termination of pupation, which lasts from four to six weeks, the 
matured fly creeps out, and, after fertilization by the male, proceeds to 
deposit ova for another generation. 

Tabular Review of Life History of Gastrophilus Intestinalis 

1. Adult Fly. — (August.) 

I 

2. Eggs. — Attached to hairs of horse (Aug. and Sept.); 

I approximately 2 weeks. 

3. Young Larvae. — Upon or within mucosa of horse's 

I mouth. 

4. Larvae (Bots). — Attached to wall of horse's stomach. 
Stages 3 and 4 approximately 10 
months. 

5. Pupae. — Free (June) ; approximatelv 6 weeks. 

6. Adult Fly.— (August.) 

Effect. — The degree of injury due to the presence of the larvae of 
this botfly will depend upon their number and location. That the 
stomach maj^ be invaded by a considerable number of bots without 
apparent disturbance to this organ is probably due to the fact that they 
most commonly attach to the esophageal portion, this region of the 
horse's stomach having a less important part in the function of digestion 



56 PARASITES OF THE DOMESTIC ANIjVL\LS 

than that toward the pyloris. Where they occupy the glandular right 
half, especially if m large numbers, thej' interfere with the digestive 
secretion and its proper contact with the gastric contents. In excep- 
tional cases they may be sufficiently nmnerous about the pyloris to 
form an obstruction to the passage of food material into the small intes- 
tine; or even the duodenum itself may be invaded. Under these latter 
conditions the larvae bring about nutritive disturbances and may cause 
attacks of acute indigestion with its accompanying manifestations of 
pain. When we consider, however, the large number of horses essentially 
harboring the larvse of the horse botfly, as indicated by the widespread 
])revalence of the insect, we must conclude that they are comparatively 
inoffensive, for in most cases there is an entire absence of any apparent 
disturbance and, with the exception of the voiding of the bots, nothing 
during the life of the animal which would lead to suspicion of their 
presence. 

Treatment. — The larvip of fiastrophilus are so resistant that treat- 
ment having in view their destruction or expul.sion has been generally 
unsatisfactory. Such agents as preparations of tar, benzine and turpen- 
tine, which are sometimes used for this purpose, add irritation to an 
already irnfated gastric mucosa and, for this reason, in connection with 
their general ineffectiveness, the advisability of their use is questionable. 
Where the presence of the bots in sufficient numbers to cause disturbance 
to the health of the animal is suspected, gastric irritation may be allayed 
to some extent by feeding mucilaginous materials, such as flaxseed meal. 
Hay in such cases is best fed chopped, and a substantial nutritive diet 
should be looked to as compensatory to the loss of nutriment. 

A treatment recommended by Peroncito and Bosso (1894) consists 
in the administration of carbon bisulphide to adult horses in gelatin 
capsules, each containing 8 to 12 grams (2 to 3 drams). After fasting for 
twelve to twenty hours, the horse is given one capsule; after one hour a 
second capsule is given, and after another hour a third. As carbon 
l)isulphide is strongly irritant, care should be taken in the administration 
of the capsules that the cap does not become detached and that they do 
not become crushed in the mouth. 

In so far as clinical observation can determine the presence of bots, or 
lead to the conclusion that a remedy has caused the expulsion of any 
considerable immber of them in projjortion to the mfestation, this treat- 
ment is said to be generally satisfactoiy. It seems reasonable to con- 
clude that an agent sufficiently active to cause the expulsion of these 
robust larvae from their secure attachment would have a severely irritant 
effect upon the gastric mucosa, though this membrane of the stomach 
appears to have a greater tolerance for such assaults than that of other 
regions of the alimentary tract. 



DIPTEROUS LARV^ 57 



Gasteophilus Hemorrhoidalis 

The red-tailed botfly. — OEstridae (p. 53). Somewhat smaller than 
G. intestinalis. Dark brown color, yellowish hairs upon the face; trans- 
verse black band upon thorax. The abdomen is covered with fine hairs 
which in the middle are dark and posteriorly orange-red. The wings are 
clear. 

This species of horse botflfj^ is found in conunon with G. intestinalis in 
North America and Europe. 

The females attach their ova to the hairs of the horse, preferably 
those about the lips. The hatched larvse cause an irritation which 
impels the horse to pass its tongue about its lips, thus carrying the 
parasite into the mouth. In other respects its life history is essentially 
the same as that of G. intestinalis. The larvae differ from those of the 
latter in being somewhat smaller and in their dark-red color. There is 
also some difference in their habitat in that they attach usually to the 
pjdoric portion of the stomach, and when fully developed pass on to the 
rectum where they remain for some time, assuming a green color before 
being voided. 

Effect. — The presence of the larvae of this fly in considerable num- 
bers in the folds of the rectal mucous membrane may cause an annoying 
irritation, inducmg violent efforts at defecation. Such cases, however, 
are extremely rare, and, as a rule, httle or no evidence is given by the 
animal of their presence. 

Gastrophilus nasalis. — CEstridae (p. 53). This species, commonly 
called the chin fly, is about 1 cm. (^/s of an inch) in length. The body is 
hairy and j'ellowish red in color. The wings are without spots. 

Law describes the larvae as "furnished with a row of spines on each 
ring from the second to the ninth on the dorsal surface, and as far as the 
tenth on the ventral. There is an unarmed part in the center of the 
eighth and ninth rmgs on the dorsal surface." 

The fly deposits its eggs about the hps and nostrils. The larvae attach 
to the mucosa of the upper part of the small uitestine. 

Fitch states (1918), as to New York State, that from examination of 
the larvae it would seem that Gastrophilus nasalis is quite as frequent 
as G. intestinalis. ^- 

Hypoderma Lineata and H. Bovis 

The ox botflies; warble flies (Fig. 29). — CEstridae (p. 53). Hypodernia 
lineata is about five-eights of an inch m length. The general color is 
black; body more or less covered with hairs. The front, sides, and back 
of the head, sides of thorax, and last segment of the abdomen are covered 
with long yellowish white hairs. 

This fly is found in all parts of the United States, but more especially 



58 



PARASITES OF THE DOMESTIC ANIAL\LS 



in the southern portion as far north as Illinois, Iowa, and Nebraska. 
It makes its appearance in the spring or early summer and is at once 
attracted to cattle, depositing its eggs on the hail's, frequently upon 
those about the heel, a haliit which gives to the fly its southwestern 
name "heel-fly." 

The entire length of the egg is 1 nnn. and its width 0.2 mm. In color 
it is a yellowish white. The eggs are firmly attached to the hairs by 
means of a clasping projec- 
tion which connects with 
the egg proper by a short 
pedicle (Fig. 31). Usually 
they are deposited upon 
the hairs in groups of four 
to si.x. 

Hypoderma Bovis. — ffis- 
tridai (p. 53). This species 
is commonly referred to as 
the Eiu'opean warble fly, 
though it occurs also in 
C'anada and the United 
States. It is, in fact, said 
to be more common in some 
jjarts of this country than 
H. lineata. Its length, ex- 
clusive of the ovipositor, as 
stated by Neumann, is 13 
to 15 mm. {]/2 to ^/s of an 
inch), which is 1 to 2 mm. 
longer than H. lineata. The 
general color is black, face 
gray; abdomen black; head, 
thorax, and abdomen hairy. 
The hairs from the base to the tip of the abdomen vary iii color from 
white or yellow to black; orange red at posterior third. The legs are 
black, yellow at their termijiations; wings somewhat brown. 

As to the differentiation of the larvae of these two species, Herms 
writes as follows: "The life history of the two species is very similar. 
The larva; are different enough to distinguish them readily. The fulh' 
grown larva of H. bovis is longer, 27 to 28 mm., H. lineata about 25 mm. 
The two species are distmguished on the basis of their spiny armature. 
In H. lineata each segment of the larva is provided with spines except 
the last, the ring upon which the stigmata are located, while in H. bonis 
all except the last two are armored." 

Life History. — Dr. Cooper Curtice, from his researches in 1890, 




Fio. 29. — Hypoderma lineata (after O.sborn, from 
Insect Life, Bui. Xo. 5, Bureau of Entomolog.v, U. S. 
Dept. of Agr.)- 



DIPTEROUS LARV^ 



59 



4 






^^— 


/^//''j^^ V". v^ 




'''■ r V X \ \\\ 


^^ fy^ /V^^ 


S8^^\\ \\\^\^ 


C-^P 


p| x^ 


I 


\ 



Fig. 30. — Hypoderma bovis (after Os- 
born, from Brauer, Bui. No. 5, Bureau of 
Entomology, U. S. Dept. of Agr.). 



concluded that the larvae of Hypoderma lineata are taken into the mouths 

of cattle by licking the parts where the eggs are attached, the eggs under 

this influence hatching at once. 

From the mouth the larva, according 

to this investigator, is carried to the 

esophagus, the walls of which it 

penetrates. While lodged in the 

esophagus it molts, and the body be- 
comes quite smooth. For a period 

of several months thereafter it 

wanders through the connective 

tissue beneath the slcin or between 

muscles, and ultimatel.y reaches a 

pomt beneath the skin of the back. 

Here the larva again molts and the 

spiny processes reappear upon its 

body. It now cuts a small opening 

through the skin, and places its 

anal spiracle near this orifice in order to get air. In this location the 

larva lives upon the products of th« inflammation which its presence 

sets up, such as bloody serous exudate and pus. It now develops rapidly 

and again molts, at which time the grub is fat, yellowish-white in color, 
and an inch or more in length. Reaching the 
maturity of its larval period (Fig. 32, g and i), 
which lasts about ten months, it works its way 
out of the orifice at the summit of the tumor 
and drops to the ground, into which it ma}' 
burrow for a short distance. Here it enters 
upon thepupal stage, the hardened larval skin 
becoming the protecting case for the pupa 
within. After aljout four to six weeks of 
pupation the adult Qy escapes bj'- pushing off 
the cap at the end of the pupal case. 

Dr. Seymour Had wen, m notes on "The 
J Life Historj^ of Hypoderma bods and H. linea- 
tum" based on observations made at Agassiz, 
Fig. 3i~Eggs of Hypo- British Columbia (Journal of the American 

derma hneata, showing clasp- .,, . . T\r i- i i • ■ t r^ -t\ 

like processes— much enlarged Vetermary Medical Association, June, 1917) 
summarizes as follows: 




(after Osborn, Bui. No. 5 
Bureau of Entomology, U. S 
Dept. of Agr.). 



"Hypoderma lineatum \a.ys its eggs as early 
as April 15th, but the usual laying period 
is during the month of May. At Agassiz they have never been cap- 
tured later than May 30th. Hypoderma bovis (Fig. 30) begins in the 
early part of June and continues up to the Ijeginning of August. 



60 PARASITES OF THE DOINIESTIC ANIAMLS 

Between the last appearances of H. lineatum and the first of H. bovis 
there is usually a period of ten days when the cattle are immune from 
attack of either species. H. bovis frightens cattle much more than 
H. lineatum. The eggs take about a week to hatch; the larvse bore 
through the skin in the coarser porous parts, taking several hours in the 
process; at this stage they are rather less than 1 mm. long. The lesions 
resulting from this penetration are caused partly bj^ bacterial invasion 
and partly by anaphylactic reactions; those produced by H. lineatum 
being more severe. For the skin lesions I have proposed the name of 
hypodermal rash. At this point there is a hiatus in the life history as it 
is not positively known how the larvse reach the esophagus, where they 
are subsequentlj' found, most likely m the loose comiective tissues imder 
the skin up to the region of the throat and into the esophagus where the 
muscles bifurcate. Passing down the esophagus they follow the sub- 
mucosa and are almost always found lying along the long axis of the 
canal. Whilst in the esophagus small edematous swellings are found 
surrounding the grubs, these are .sterile and are anaphylactic in char- 
acter, the exudate contains large numbers of eosinophilic leucocytes but 
no pus cells. The earliest record made at Agassiz was on August loth, 
when a larva 3.4 mm. was foimd and several slightly larger. According 
to Carpenter, continental observers have found them smaller than this. 
//. lineatum makes its appearance in the backs of cattle about Decem- 
ber 15th and H. boris about a month later. The larvae at this time have 
grown to about 1.5 cm. and are of the same size m the neural canal and 
under the skin which they have just reached. At this age it is difficult 
to separate the larvse of the two species, but Mr. F. C. Bishopp has, I 
believe, discovered good distinguishing marks between the species. The 
life histories overlap at this period making it difficult to follow the 
migration, but in the latter part of the season (the middle of March) 
the last larva; to leave the gullet are at the paunch end. They pass out 
under the pleura and go to the neural canal either up the crura of the 
diaphragm or up the posterior border of the ribs, entering the canal by 
the posterior foramen, from there they descend the canal under the 
dura mater, emerge again through the foramen and reach the back, 
forming the characteristic swellings commonly called warbles. The 
larvse follow connective tissue exclusively and no larvae have been dis- 
covered in muscular tissue. The mature larvse leave the animals' backs 
from the early part of the year up to the first days of July. The periods 
for the two species have not been fully worked out, but judging from 
what records we have of the pupal period and the time of year the flies 
are about, H. lineatum begins to emerge in February and finishes about 
May 1st. H. bovis begins al)out May 1st and ends approximatel.v on 
July 1st. The average pupal period for H. bovis is 32.5 days and for 
H. lineatum a little less. The duration of the life of the flies is short 



I 



DIPTEROUS LARViE 



61 




62 PARASITES OF THE DOMESTIC ANIMALS 

seeing that they cannot feed. This hfe history apphes to Agassiz, 
British Cohnnbia; doubtless in other countries variations will be noticed, 
but the period sjjent by the larvae within the host must be of the same 
diu-ation, seeing that animals' temperatures are the same the world over." 

Effect. — Cattle seem to be much annoyed by the attacks of these 
flies in depositing their eggs, and in the endeavor to escape will often 
enter mire holes or injure themselves in other ways. Probably the most 
important damage from the insect is that to hides, these being dis- 
counted from twenty-five to fifty per cent, according to the number of 
punctures by the grubs. 

Treatment. — Treatment is best applied in the months of January 
and Fel)ruarv when the grubs have become sufficiently developed that 
the small tumors in which they are lodged may be felt by running the 
hand along the back of the animal. The application at this time of a 
little kerosene or mercurial ointment to the summit of the swelling will 
destroy the gi-uli. B>' March the tumors may be distinctly seen as 
prominent luni]is upon the skin of the back. The orifice at the summit is 
now large enough to jK'rmit of the forcing out of the grub bj^ careful 
pressui'e. (irulis thus removed should be at once destroyed to prevent 
the possibility of their finding favorable conditions for development 
into the adult fly. 

(ESTRUS Ovis 

The sheep botfly (Fig. 33, 1 and 2).— CEstrida; (p. 53). About one- 
half an inch in length ; yellowish-gray color ; slightly hairy. The abdomen 
is sjKjtted with white and yellow; posterior portion covered with fine 
bail's. The wings are transparent. 

Occurrence and Life History. — This species is of world-wide dis- 
tribution, and is the most important insect pest with which sheepmen 
have to deal. The flies make their appearance with the coming of warm 
weather from early June to July, like other ffistridae, flying on bright 
and warm days and ceasmg their activities about the month of October. 
The female, which is difficult to observe owing to its small size and rapid 
flight, deposits living larvEe in the nostrils of the sheep. At this time 
the lai-va is cream>'-white in color and about one-sixteenth of an inch 
in length (Fig. 33, 6). Later it becomes darker, and at maturity reaches 
a length of about three-quarters of an inch (Fig. 33, 4 and 5). Upon the 
cephalic segment there are two booklets the points of which are curved 
downward and backward. With the aid of these the larva at once pro- 
ceeds to work its way upward through the nasal passages until it reaches 
the frontal sinuses where it attaches by its booklets to the lining mem- 
brane. Here it feeds upon mucus and serous exudate induced by the 
irritation of its presence. 

The larva remains in this location about ten months, at the end 



DIPTEROUS LARV.E 



63 



of which time, having reached its larval maturity, it detaches from the 
mucous membrane and passes to the nasal passages from which it is 
expelled by the violent sneezing which it excites in its host. Having 
reached the groiuid, it quickly buries itself, contracts within its smooth 
dark shell, and enters upon its pupal stage (Fig. 33, 3). After from four 
to six weeks of pupation the mature insect emerges. 

Effect. — Both sheep and goats suffer from the attacks of this fly. 
Sheep are especialh' disturbed by it, and in their efforts to avoid its 
attack will toss the head, thrust the nose into the ground, or dash about 
in frenzy. The grubs cause much 
irritation to the sensitive mem- 
brane which lines the cavities of 
the head both by the hooklets 
with which they make their at- 
tachment and by the spines cov- 
ering the ventral region. Further- 
more, if nunierous, and the mucus 
secreted is not sufficient for their 
nourishment, the grubs will feed 
upon the membrane itself. The 
disturbance to the host will be 
manifest according to the number 
of grubs present; if there are but 
few, there may be no more than 
a slight cataiThal discharge with 
occasional sneezmg. In heavj' 
infestation there is a profuse 
muco-pumlent nasal discharge with frequent sneezmg and tossing of the 
head, the respirator}^ passages in some cases becoming so filled as to 
bring the animal to the verge of suffocation. The appetite is lost, and 
emaciation and weakness may progress until there is inability to rise, 
death in such cases soon followmg. 

Tabular Review of Life History of CEstrus Ovis 

1. Adult Fly. — (June to October.) 

A 

2. Hatched Embrvos. — Deposited in nostrils of sheep. 

3. Larvse. — Attached to lining membrane of sinuses of 

I sheep's head. Stages 2 and 3 approximately 

I 10J4 months. 

4. Pupae. — Free; approximately 6 weeks. 




Fig. 33. — CEstrus ovis: 1 and 2, adult fly; 
3, pupa; 4, full-grown larva, dorsal ^^ew; 
5, same, ventral "^new; 6, young larva. 1 and 
2 natural size, the others enlarged (after 
Osborn, from Riley, Bui. No. 5. Bureau of 
Entomology, U. S. Dept. of Agr.). 



5. Adult Flv 



64 PARASITES OF THE DO^NIESTIC ANIMALS 

Treatment. — The location of the grubs and the tortuous extremity 
of the canals leadmg to such regions render the application of remedies 
looking to their dislodgment but partly effective at best. Benzene ap- 
plied' by lifting the head and pouring a teaspoonful into each nostril, 
has been recommended. As one side is treated the head should be 
held elevated and the nostril held shut for half a minute. The remedj' 
is then likewise applied to the other side. In severe cases a few of the 
grubs may be dislodged by a feather dipped in turpentine which is 
passed as far as possible up the nasal passage and rotated so as to apph' 
it to as much of the surface as can be reached. Valuable breeding 
animals showing severe infestation may be treated by trephining the 
simises. 

Prevention. — To prevent the fly from depositing its larvae the noses 
of tiie sheep may be smeared with tar. For the convenient application 
of this preventive remedy many flock owners use salt logs in their pas- 
tures. Into these logs two-inch holes are bored at intervals of about 
six inches in each of which a little salt is kept during the fly season. 
Two or three times a week tar is smeared with a brush aroimd these 
holes in such manner as to smear the noses of the sheep as they en- 
deavor to reach the salt. The logs should be of sufficient length to enable 
ail the sheep to get to them. 



CHAPTER VII 

THE FLEAS 

Order II. Siphonaptera. — Insecta (p. 15). Members of this order 
have the body compressed laterally, and the color is usually dark brown. 
The head is small, generally bearing a single ocellus on each side, com- 
pomid eyes are absent. The mouth parts are suctorial but differ from 
those of the order Diptera in that the true haustellum is lacking, the 
sucking structure consisting of the ventrally grooved labrum and the 
two mandibles, which form a half-open tube (Fig. 36, e and f). The 
maxillae are sharp and serve to puncture the skin. The three thoracic 
segments are distinct, each bearing a pair of well-developed legs, the 
posterior pair bemg especially long, powerful, and adapted for leaping, 
which is the principal mode of progression. 

Metamorphosis is complete. The larvaj are long, slender, without 
feet, and somewhat hairj^. When mature the larva spins a cocoon and 
enters upon a distinct pupal stage. During this stage the pupa takes 
the form of the adult with the appendages enveloped in a hard pupal 
case. At no stage in the metamorphosis are there traces of the supposed 
ancestral wings. It is probable, however, that the fleas have descended 
from winged forms, and they are usually considered as being closely 
related to the Diptera. 

There are many species of fleas, most of them inhabiting various wild 
birds and mammals. It will be sufficient here to consider the following 
three of the family Pulicidse : 

1. Ctenocephahcs canis, the dog flea. 

2. Ctenocephalus felis, the cat flea. 

3. Pulex irritans, the human flea. 

The two species of Ctenocephalus can easil.y be distinguished from 
Pulex by the presence in the former of comb-like spines on the lower 
margm of the head and on the hinder margm of the prothorax. These 
spines are dark colored, stout and closely placed (Figs. 34 and 35). 
The dog and cat flea have long been placed together under the one 
species Pulex serraticeps, but a later classification recognizes a specific 
difference based principally upon the form of the head. In Ctenoceph- 
alus canis the head, when seen from the side, is rounded in front and 
somewhat less than twice as long as high. The head of C. felis, seen from 
the side, is more acute angled in front and is long, being fully twice as 
long as high. The head of Pulex irritans, with its absence of spines, is 



66 



PARASITES OF THE DOMESTIC ANIMALS 



more regularly rouiuled than that of the dog flea, and Ijears two bristles, 
one low, in the vicinity of the maxilla, the other below the eye. 

Life History. — In their life history the fleas undergo a complete 
metamorphosis. The eggs are oval, 0.5 mm. in length, and in color 
pearly white (Fig. 36, a). They are deposited loosely and unattached 
among the hairs of the host, dropping off readily during the movements 
of the animal. The period required for the eggs to incubate may be 
fi'om one to four days or longer, depending much upon temperature. 

The larvae are white, elongate, apodal, and have thirteen segments, 
each provided with bristles (Fig. 37). They are very active and, avoiding 
the light in ovny way possible, seek such shelter as is afforded by crev- 





FiG. 34. — The dog flea, anterior 
portion of body (after Osborn, Bui. 
No. 5, Bureau of Entomology, 
U. S. Dept. of Agr.). 



Fig. .3.5. — The human flea 
(Pulcx irrit.ans), anterior por- 
tion of body (after Osborn, 
Bui. No. 5, Bureau of Entomol- 
ogy, U. S. Dept. of Agr.). 



ices in the floor, carpets, rubbish, or bedding of kennels, such material 
containing fecal or other organic matter upon which they feed, being 
especially favorable for their tievelopment. 

The length of the larval .stage varies con.siderably under the influence 
of temperature. It may be from seven to thirty days, during which 
time there are two molts. Just before entering the pupal stage the 
larva spins a white .silken cocoon within which the pupa (Fig. 36, c) is 
lodged (Fig. 36, h). Transformation to the fully developed imago — 
again depending upon temperature and moisture — will occupy from 
Ave to ten days. The time requii'ed for the development of the mature 
in.sect from the deposited egg is, therefore, from thirteen to forty-four 
days, with twenty-eight days as probably a fair average luider our 
ordinary climatic conditions. 

Habits and Relation to Disease. — Nearly all species of fleas have 
some one host upon wliich they pief(>r to live, but they will often live 
and thrive upon other animals. The human flea will infest dogs and 



THE FLEAS 



67 




68 



PARASITES OF THE DOMESTIC ANIMALS 



cats and may be found upon these animals in conmion witli the species 
usually infesting them. As a pest of the household the human flea is 
more conmionlj^ found m Europe and the western part of the United 
States, while in the eastern United States houses may be rendered un- 
inhabitable for a tune by the presence of the dog and cat flea. 

Fleas are of importance as tormenting parasites of man and domestic 
animals, but of late have received greater attention in the field of med- 
icine as carriers of disease. It is known that bubonic plague, which 
during recent years has made its appearance on the Pacific and Gulf 
coasts of the United States, is transmitted bj- these msects. Taeniasis 
of the dog, due to the presence of Dipijlidium caiii- 
num, may be conveyed to humans as well as to dogs 
through the intermediation of the dog flea, while a 
disease of infants known as kala azar, occurring 
in countries bordering on the Mediterranean, is 
thought to be transmitted by fleas. 

Usual Hosts. — Our larger domestic animals, such 
as horses, cattle, and sheep, are rarely attacked b.y 
fleas. Hogs arc somewhat less free from them, but, 
if occurring in these animals, the infestation is most 
alwaj's light and causes little disturbance. Dogs, 
cats, rabbits, fowls, and pigeons are especial ob- 
jects of attack. Young dogs and those chained 
up are more likely to be infested as they live amid 
conditions favorable to the breeduig of the insects 
from the laj'ing of the eggs to their full develop- 
ment, which is particularly favored by litter and 
wooden floors. Unlike lice, fleas do not pass their 
entire cycle upon the host, nor are they limited to a particular species. 
The dog and cat flea will readily attack man, and in this coimtry is more 
troublesome to him than the human flea. 

Vitality. — When feeding upon blood, which is the only food taken 
hy the adults, fleas wifl live from several months to a year. Off a host 
the dog and cat flea will not survive longer than about two months, the 
length of life under such conditions being considerably shortened if the 
weather be hot and diy. 

Treatment and Control. — Where habitations are infested by these 
insects it is of first miportance as a measure of control that dogs, cats, 
and other domesticated anunals kept about the premises receive treat- 
ment that will rid them of the parasites. The harboring animals ma}' 
be dusted with Persian insect powder (pyrethrum), the remedy being 
applied liberally and driven well under the hair, preferably after the 
skin has been slightly moistened. This will not kill the fleas but will 
stupify them, in which condition they will drop off or may be combed 




Fig. 37. — Pulex irri- 
tans, larva. 



THE FLEAS 69 

from the hairs. It is well to place the animal while undergoing this 
treatment upon a large sheet of paper which may later be rolled up and 
burned with the collected fleas. In severe cases creolin or lysol solutions 
in two per cent, strength may be used. Quite effectual, but more expen- 
sive, is the preparation consisting of Peruvian balsam, ten parts; creolin, 
two parts; alcohol, one hundred parts which is recommended in the 
treatment for lice and scab mites upon small annuals. In the treatment 
of cats, puppies, and chicks the powder is preferable to the last men- 
tioned preparations. 

Following treatment animals should not be permitted to re-enter 
their sleeping quarters until all litter has been removed and burned. 
In order that this cleaning up process may be effectual every detail 
must be looked to. Collections of dirt and dust between floor boards 
must be removed, as well as every particle of bedding or rubbish that 
may harbor a flea brood. After this preparation the quarters should be 
thoroughly cleaned with hot, soapy water and, when dry, sprayed with 
kerosene or kerosene emulsion (formulae, page 48) as an additional pre- 
caution. For kennels a bedding should be used which can be frequently 
replaced, as shavings or straw. Carpet or matting should never be used 
for this purpose. 

Household Infestation. — In dealing with household infestation it is 
first necessary to exclude flea-bearing animals from the premises or 
destroy the adults which are producing the eggs upon these hosts. Flea 
larvae find excellent conditions for development under tacked-down 
carpets or matting and in spaces between floor boards. The floor 
covering, whatever it may be, should be removed, beaten, and thor- 
oughly aired. The floors may then be swept and the dust, which con- 
tains many eggs and larvae, collected and burned. Kerosene should 
then be applied Avith a mop in such- manner that it wiU penetrate all 
cracks and crevices in the floor and beneath the baseboards. Benzene 
is often advised for this purpose, but, owing to the extreme danger of 
ignition, its use, excepting under the most careful supervision, is not 
to be recommended. 

Following these eradicative measures the floor coverings may be re- 
placed, but before domg so it is well, as an additional precaution, to 
sprmkle the floors with pyrethrum powder. This will work into the 
fabric and make the carpet or matting an unfavorable harbor for any 
larvae or adults which may have escaped the eradicative measures. 
AVhere the floors are oiled and rugs used instead of carpets or matting, 
the problem of gettu:g rid and keepmg rid of such an infestation is much 
lessened. 



CHAPTER Viri 

THE LICE 

There has been much disagreement among various authors as to the 
systematic arrangement of the hce. The classification given here, if 
faulty, will perhaps at least serve the purposes of this work until exacting 
systematists have better settled the matter. 

Order III. Siphunculata. — Insecta (p. 15). The Sucking Lice. — The 
lice of the order Siphunculata have the suctorial mouth parts at the 
anterior border of the head, the movable proboscis lieing formed of the 
upper and lower lips (Fig. 38). Within this is the .sucking-tube which is 
projected beyond its sheath and buried in the skin when used to aspirate 
blood. The eyes are two simple ocelli, one on each side. The antennse 
are short. The thorax is usually broader but shorter than the head, with 
indistinct division into three segments. The legs are short and thick, the 
tarsi termiiiatLng in a single claw. There ai-e no wings. The abdomen 
is large and generally elliptical in outline. The last abdominal segment 
is rounded in the male with an opening for the penis. In the female 
this segment is notched and has two small terminal appendages. The 
female is from L.5 to 5 mm. in length, the male somewhat smaller. 

Life History. — The metamorphosis is incomplete. The young, which 
lea\c the eggs In' an operculum, have the shape of the adults but do not 
acquire the adult color and consistency until after several molts. 

The eggs as they are extruded from the female are glued fast to the 
hairs of the host by means of a viscid secretion. In this position they 
are commonly referred to as nits, which, with the aid of a hand glass, 
will be observed to have somewhat the shape of a l)arrel with the at- 
tached end rounded and a blunt free extremity (Fig. 40, e). 

Hatching occurs in from five to six days, the young in general re- 
sembling the adults excepting in size. They become mature in about 
foiu- weeks. 

The sucking lice come into one family, the Pediculidte. All are per- 
manent parasites, the entire life cycle being spent upon the host. All 
are limited to a specific host, and will only accidentally inhabit a host of a 
different species. Therefore if the host is known, the specific identity 
of the parasite is readily determined. 

The characteristics of the species are here given under their respective 
host animals. It may be said of the sucking lice in general that the head 
is inserted directly on the thorax, their antennae are five-segmented; the 



THE LICE 71 

segments of the abdomen number eight or nine, and their tarsi are 
terminated by a single claw. 

Order IV. Mallophaga 

The Biting Lice. — Insecta (p. 15). The members of the order of 
biting lice resemble the sucking lice in general form, but differ from them 
mainly in that they are much smaller and have the mouth parts adapted 
for biting and mastication. They may be at once distinguished b.y the 
head and mouth parts; the head is usually rounded, triangular, squared, 
or crescent-shaped, and is broader than the thorax (Fig. 39). Upon the 
under side of the head are located the mandibulate mouth pieces adapted 
for cutting and feeding upon epidermic scales, hairs, feathers, and 
other cutaneous products. The ej'es are simple ocelli located back 
of the short antennae and are often indistinct. The thorax is generally 
narrow, the prothorax bemg distinct, the two posterior segments fused. 
The legs are adapted for either clasping or running; in the first case the 
tarsi terminate in a single claw (Philopteridse), in the second the tarsi 
are long and terminate in two claws (Liotheidse). Wings are absent. 
The abdomen is generally elliptical; it may be elongate, or short and 
broad, approaching a glolDular outline. Their relativeh' small size and 
hard, flattened bodies facilitate their movement among the hairs close 
to the bodj'. 

In their breeding habits and life history the Mallophaga agree with 
the preceding order. 

Although the order has been variousl^y subdivided, it will be sufficient 
here to place the biting lice according to their hosts in the two families 
Philopteridse and Liotheidte, the former including the biting lice of 
mammals and .birds, the latter the lice of birds only. 

Biting lice, like the suctorial, are limited to a specific host, which as a 
rule they do not voluntarily leave imless it is to crawl upon another 
host of the same species, in which case the migration is ordinarily ac- 
complished when the bodies of the host animals are in contact. Under 
conditions of severe infestation among poultry some of the parasites 
may pass to the roosts and nests and, by contact, even to the body of a 
mannnalian host, but they will not survive such migrations for more than 
a few hours. 

Pediculosis of Domestic Mamalils 

The condition commonly known as lousiness is medically referred to 
as pediculosis, a term correctl}^ applied whether the condition be due 
to the presence of either the sucking or the biting species. The term 
phthiriasis should properly be restricted to ijifestation with the genus 
Phthirius in particular. 

Lousiness is usualh- accompanied by an unthrifty condition, not 



72 PARASITES OF THE DOMESTIC ANIMALS 

necessarily resulting from, but rather predisposing to the attack, the 
reduction in the functional activity of the skin in such condition afford- 
ing an ijiviting habitat for the parasites. Herbivorous animals which 
have been kept for a prolonged period upon dry feed, as during the 
winter months, are those most likely to be infested, lice rarely being 
found upon these animals after they have been turned upon more 
succulent food and the winter coat has been shed. 

There is, m fact, little valid e.xcuse for the presence of these parasites 
upon our domestic animals at any time. Infestation is usually the 
accompaniment of uncleanly, impoverished, and crowded conditions of 
stabling or yarding. Well housed, well fed, and regularlj' groomed 
animals offer no attractions to lice, and anmials so cared for will not 
have them. Excepting in accidental and transient incidents, their pres- 
ence upon man or domesticated beast reflects upon man in either case. 

Whether the degree of discomfort and injury to an animal due to the 
presence of lice upon its body is slight or serious in its consequences will 
depend upon the number present and the group to which they belong. 
The sucking lice, piercing the skin and feeding upon the blood and 
exudate, cause a much more intense pruritus than that occasioned by 
the biting lice which, in their habit of feeding upon surface epidermic 
products and d6bris, have more the nature of scavengers. 

The presence of the lice, as well as their location, is indicated by the 
pnuitus, by their eggs or nits upon the hairs, and the d6bris of their 
molts. The irritation of the itching and rubbing, together with the loss 
of blood if suctorial lice are numerous, results in emaciation and general 
imthriftiness of an animal likely to have been in poor condition before 
becoming infested. 

AVliilc the presence of lice may be unmistakably evident, it should 
be made quite sure that there is not also ]iresent a form of acariasis. 
Lice fi-equently invade animals suffering from scabies, and the pruritus, 
with the accompanyhig scaly and scabby condition of the skin, may be 
due to scab mites, which, minute and deeply located, mav be readily 
ovei'looked. The jiresence of these can only l)e determined with cer- 
tainty by examination of epidermic scrapings from beneath the scabs. 
For their detection and examination the microscope is necessary. They 
are, however, often difficult to discover, and the nraterial is best sub- 
mitted to a laboratory for examination if such is available. More de- 
tailed methods of diagnosis and treatment of this condition are given 
elsewhere under the discussion of the scab mites. 

Pediculosis of the Horse 

Horses, mules, and asses harbor one species of sucking louse, Hcema- 
topinus asini, and two species of biting lice, Trichodedes equi and T. 
pilosus. 



THE LICE 



73 



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* 


^ra 


1" 


W^P 


r 


w 


' 




1. Haematopinus asini (H. macrocephalus) . — Pediculidse (p. 70). 
Head long and narrow; antennse attached at lateral protuberances be- 
hind which are notches lodging the eyes. Anterior to this the head is 
more narrow with borders parallel, terminating 
in a blunt point. The thorax is much shorter 
than the head and widens posteriorly. The 
abdomen is oval, with stigmata placed in the 
middle of lateral protuberances on the margins 
of segments. The general color is yellow, the 
thorax brownish. The female is 3 to .3.5 mm., 
the male 2.5 mm. in length (Fig. 38). 

2. Trichodectes equi (T. parumpilosus) . Phil- 
opteridae (p. 71). — Head slightly longer than 
broad and semicircular in front of the antennae 
which are set well back. The abdomen is oval 

and bears eight trans- 
verse dark bands, each 
upon the anterior por- ^ „ , 

,■ c ,1 Fig. 3S. — Haematopinus 

tion of a segment and ^^i^i (after Osborn, from 

extendmg from the Comstock, Bui. No. 5, 

middle Ime about half- Bureau of Entomology, U. 
. . S. Dept. of Agr.). 

way to the margm. 

The general color of the abdomen is yellowish, 
the head, thorax, and legs chestnut (Fig. 39). 
3. Trichodectes pilosus. Philopteridae 
(p. 71). — Somewhat smaller than the preced- 
ing species. Head broader than long, rounded 
in front, and slightly widened at the temples. 
The antennae are inserted well forward, almost 
on a line with the head's anterior border, in 
which respect it markedly differs from T. equi. 
The aljdomen tapers posteriorly and has upon 
the middle ofthe first seven segments darkened 
spots, less conspicuous than the bands simi- 
larly located upon T. equi. The head, thorax, 
legs, and abdomen are hairy on both surfaces. 
The general color is yellow. 

Pediculosis caused by suctorial lice upon the 
horse is usually located at the base of the mane 
and forelock, and at the root of the tail. The hairs about these parts 
are likely to be scant, broken, or the skin entirely denuded, due to 
the rubbing against anything within reach. During the act of rubbing 
the animal has a peculiar habit of protrudmg the upper lip, or, if in 
reach of another animal, will gentlv bite it. 



Fig. 39. — Trichpdectes 
parumpilosus (after Osborn, 
Bui. No. 5, Bureau of Ento- 
mology, U. S. Dept. of Agr.). 



74 



PARASITES OF THE DOMESTIC ANIMALS 



Biting lice are less common upon horses than suctorial. They are not 
often found on the upper parts of the body, more frequentlj' occupying 
the regions of the neck, breast, and between the fore and hind legs. 
They cause less pruritus than the sucking lice, though the animals will 
freciuently rub bare places at the regions infested. Both forms may 
coexist upon the same animal. 

Pediculosis of the Ox 

Two species of suctorial lice inhabit the ox, Hcematopinus eurysternus, 
— the short-nosed ox louse, and Linoynathus vituli, — the long-nosed ox 
louse. Of the biting species there is but one, Trichodedes scalaris. 

1. Hsematopinus eurysternus. Pediculidie (p. 70). — Head relativelj' 
short and broad, rounded in front; thorax about twice as wide as long. 




Fig. 40. — HfEmatopinus eurysternu.s: a, female; b, rostrum; c, 
ventral surface of the last segments of male; d, same of female; e, egg; 
f, surface of same greatly enlarged (after Osborn, Bui. No. 5. Bureau 
of Entomology, U. ,S. Dept. of Agr.). 

widest posteriorly. The abdomen is oval and nuich larger than that of 
the sucking louse of the horse. On the lateral margin of each abdominal 
segment is a slightly colored tubercle. In the female two black blotches 
are laterall.y located on the terminal segment. The general color is 
3'ellowish grav. The female is 2 to 3 mm., the male 2 mm. in length 
(Fig. 40). 

2. Linognathus vituli (Hsematopinus vituli). Pediculidte (p. 70). — 
Somewhat smaller than the preceding. The head is long and narrow 
and somewhat sunken in the thorax, as m a notch. The thorax is about 
as broad as long. The abdomen, like the head, is long and narrow, 
giving to the entire insect a long and slender appearance. The general 
color is a deep chestnut. The female is 2.5 to 3 mm., the male 2 to 2.5 
nun. in length (Fig. 41). 



THE LICE 



75 





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- 




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f^n 




St 




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I 


C -J 


\ 


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r 
r 


^ 




This species is found upon calves, though it will also, — probably as 
frequently, — infest adults. 

3. Trichodectes scalaris. Philopteridee (p. 71). — Head cone-shaped, 
rounded at the temples and in front, about as broad at the temples as 
long. The antennae are inserted well back 
and are usually directed backward. The ab- 
domen is not so tapering as in the biting louse 
of the horse, and the median spots are larger, 
forming bands which are quite distinct. The 
general color is white. It is somewhat smaller 
than the species infesting the horse (Fig. 42). 
This is a very common and widely dis- 
ti'ibuted species, frequently found upon cattle 
in cohabitation with the sucking lice. 

Pediculosis of 
the ox, caused 
by either the 
short or long- 
nosed species, 
is most likely 
to be found 
about the ears, 

base of the head, and along the dorsal 
line of the neck, back, and loins. The 
intense itching causes the animal to rub 
against any convenient object, and there 
is frequent licking of the parts which can 
be reached with the rough tongue. As a 
result of this rubbing large patches of 
skin may be entirely denuded of hair, 
and the skin itself in severe cases may 
become pustular and scabby. 

Contrary to what has been observed 
in the horse, biting lice probably occur 
more frequently upon the ox than the 
sucking species, therefore lousiness of 
cattle is usually accompanied by less 
itching. As to their location the biting lice of cattle do not limit them- 
selves, usually' spreading to all parts of the body. They may frequently 
be observed crawling out upon the hairs and, when one is removed and 
examined with a hand glass, one or more hairs will often be found in the 
clutch of its claws. 



Fig. 41. — Hsematopinus 
vituli: female, under surface 
of last segments of abdomen 
of same (after Osborn, Bui. 
No. 5, Bureau of Entomol- 
ogy, U. S. Dept. of Agr.). 



Fi(j. 42. — Trichodectes scalaris 
(after Osborn. Bui. No. 5, Bureau 
of Entomologj-, U.^ S. Dept. of 
Agr.). 



76 



PARASITES OF THE DOMESTIC ANIMALS 



Pediculosis of the Sheep 

This animal has one suctorial louse, — Linognathus pedalis, and one 
biting louse, — Trichodcdes sphceroccphalus. 

1. Linognathus pedalis (Haematopinus pedalis). Pediculidse (p. 70). 
— Ha.s the same general shape as the short-nosed ox louse, but is 
somewhat more slender. It is also much lighter in color, giving it a 
somewhat immature appearance (Fig. 43). 




Fig. 4.3. — Haematopinus pedalis; a, adult female; b, ventral view of terminal seg- 
ments of same; c, terminal segments of male; d. egg (after Osborn, Bnl. No. 5, Bu- 
reau of Entomology. U. S. Dept. of Agr.). 

This s]K'cies is rare. It is said to occur only where the hair is short 
upon the legs and feet, especially about the dew-claws. It is from this 
location that it gets its common name, "sheep-foot-louse." 

2. Trichodectes sphaerocephalus. Philopteridje (p. 71). — Head 
broad as long, giving the rounded ajipearance from which the specific 
name is derived. The abdomen is elliptical, each segment having a 
median band which is somewhat roimded upon its anterior border. 
The general color is white (Fig. 44). Of rather rare occurrence. 

The conunon so-called "louse" of sheep is not a true louse, but the 
degenerate fly Mdophagus ovinus, described elsewhere under the par- 




THE LICE 77 

asites of the order Diptera. Pediculosis, properly so called, is seldom 
met with in sheep. While the sucking lice are localized to the lower 
parts of the legs, the biting lice lie deep in the wool, close to the body, 
seriously altering the fleece bj^ cutting the fibers with 
their mandibles. Their location makes the condition 
rather a difficult one to contend with. 

"Pediculosis of the Goat 

Goats have one suctorial species, — Linognathus stenop- 
sis. The biting louse, — Trichodectes climax, is fairly com- 
mon and is the onl_y species of this genus upon goats that 
is well established. _.j,^.. 

1. Linognathus stenopsis (Haematopinus stenopsis). ehodectes spha;- 
Pediculidffi (p. 70). — Head long, narrow, and rounded in rocephalus (af- 
front; there are two lateral notches, below which are ^" ^t"^"^" ^"'' 

• 1 1 -n 111 -11 "°- ^' Bureau 

widened temples. From these the head narrows rapidly of Entomology, 
and becomes deeply fitted into the thorax. The thorax u. s. Dept. of 
is widest posteriorly where it is somewhat concaved upon ^^''' 
the abdomen. The abdomen in outline is an elongated oval with stig- 
mata near lateral margins of segments. The female is 2 mm. ; the male 
1.5 mm. in length. 

2. Trichodectes climax. Philopteridse (p. 71). — Head quadrangular 
in shape and broader than long. The abdomen is oval with median 
dark bands upon the segments. The head and thorax are reddish 
brown ; the abdomen is pale j^ellow. 

During the winter months especially, goats are apt to harbor lice in 
rather large numbers. As in other animals the sucking louse produces 
the greater irritation. The skm may become bare in places with numer- 
ous inflamed" and ulcerated areas covered with crusts. In Angora goats 
especially, the biting louse causes a great depreciation from its habit of 
cutting the hairs with its mandibles. 

Pediculosis of the Hog 

Domesticated and wild hogs have one species of louse, Hcematopinus 
suis (H. ufius). This is the largest loiown member of the suctorial 
group. The he^id is very long and narrow, cone-shaped, and rounded 
in front; just posterior to the attaclunents of the antennae are horn-like 
protuberances, forming deep notches. The thorax is somewhat broader 
than long; dark, transverse bands may be noted upon the legs. The 
abdomen is oval in outline, with distinct segment borders; the stigmata 
are upon prominent lateral protuberances. The thorax is brownish 
red in color; the head and abdomen yellowish gray. The female is 5 
mm.; the male 4 mm. in length (Fig. 45). 

This louse is a very active blood sucker, living upon hogs of any age 



78 



PARASITES OF THE DOMESTIC ANIMALS 




or condition and everywhere where tliese animals are found. The 
intensity of the pruritus produced is proportionate to the parasite's 
size, the skin, as they increase in numbers, becoming covered with 
papules and scales. The constant itching and worry, which seems to 

be most severe at night, is evidenced 
by the restlessness of the animals 
and their violent scratching against 
any available object. Such a con- 
dition seriously interferes with the 
growth and fattening of hogs, and 
young pigs especially will often 
succumb to loss of blood and ex- 
tensive irritation and excoriation 
of the skin. 

Pediculosis of the Dog 

Dogs have one sucking louse, 
Litwgnathus piUferus and one biting 
louse, Trichodedes latus. 

1. Linognathuspiliferus (Haema- 
topinus piliferus). Pediculidse 
(p. 70). — Head thick, about as wide 
as long, rounded 
in front. The 
thorax anteri- 
orly is but slightly wider than the head; abdomen 

elongate oval in outline, the margins of the segments 

apjiearing somewhat rounded; stigmata marginal and 

distinct. The general color is yellowish white. The 

female is 2 nun. ; the male 1.5 mm. in length (Fig. 46). 
2. Trichodectes latus. PhilopteridiE (p. 71). — 

Entire in.'^ect Jjroad and shoi't; more than half as 

broad as long. The head large, slightly rounded in 

front, and broader than long. The abdomen of the 

female is broad and somewhat globular in outline. 

The median abdominal bands or spots are absent. 

The general color is bright yellow (Fig. 47). 

Dogs do not seem to be as seriously affected as Bureau of Entomol- 

other animals by the presence of lice. The sucking f^^-^ ^- ^- °<=p*- °^ 

louse is the more tormenting, and is usually found 

about the chin, imder part of the neck, and breast, though, with the 

biting louse, it may be found on any part of the body. The biting 

species is most often found upon puppies. 

The biting louse infesting dogs is particularly of medical interest in 



Fit;. 4."). — H^matopinus suis (from 
liliiitoKiapli of mounted spedmen, by 

Hurilt). 




Fig. 46. — Haemato- 
pinus piliferus (after 
Osborn, Bui. No. 5, 



THE LICE 



79 



being a larval host of the common tapeworm of the dog, Dipylidium 
caninum, as is also the clog flea, Cienocephalus canis. Infection of the 
louse by the larva (Cysticercus trichodedes) is readily brought about 
through ingestion of the eggs of the tapeworm which may have col- 
lected about the anus or in the htter of the kennel. 
This tapeworm is occasionally found to be present in 
the intestines of human beings, particularly children. 
It is quite conceivable how such infestation might 
occur in the fondling of lousy or flea-infested dogs, 
especially if the person's food be about at the same 
time to act as a vehicle for the insects containing the 
larva. 

Pediculosis of the Cat 

Trichodectes subrostratus, the only louse harbored Fig. 47. — Xri- 
bv the cat, is about the same length as the biting louse ^hodectes latus 

r ,1 1 /I . 1 .T \ u i. • i (after Osborn, from 

of the dog (1 to 1.3 mm.), but is not so Denny, Bui. No. 5, 

broad, and is distinguished by its pointed Bureau of Ento- 
head, which is slightly longer than broad. ™f°|^''f^^^ ^- ^- ^''^^■ 
The abdomen is oval, with median bands. 
The head and thorax are bright yellow in color, the abdo- 
men whitish (Fig. 48). 

Lousiness is not often met with in the cat; when it does 
occur it is usually the accompaniment to a debilitated 
condition in young animals. 

Pediculosis of Man 





Fig. 48.— 
Trichodectes 
subrostratus 
{after Os- 
born, Bui. 
No. 5, Bu- 
reau of En- 
tomology, 
U. S. Dept. 
of .\gr.). 



Three species of pediculi infest man, Pediculus humanus 
{P. capitis), the head louse, P. corporis (P. vestimenti) , the 
body louse, and Phthirius pubis {P. inguinalis) the pubic 
or so-called "crab-louse." 

L Pediculus humanis. Pediculida; (p. 70). — The head 
is somewhat diamond-shaped, short, and about as broad 
as long. The abdomen has seven distinct segments, each 

bearing stigmata laterally placed. Color gray with darkened margins. 

The color is said to vary from light to dark according to the color of 

the skin or hair of the host. The female is 2.5 to 3 mm. ; the male about 

2mm. in length. 

2. Pediculus corporis. Pediculidse (p. 70). — Resembles preceding 
species, of which it is regarded by some authorities as merely a variety. 
It is slightly larger. The color is grayish-white. It lives upon the 
clothing of its host, crawling upon the body to feed. 

3. Phthirius pubis. Pediculidae (p. 70). — Distinctly differs in ap- 
pearance from the two preceding. The head is short and thick, fitting 



80 PARASITES OF THE DOMESTIC ANIMALS 

into a broad concavity in the thorax. The thorax is liroad and appar- 
ently fused with the abdomen, the two forming a somewhat heart- 
shaped body with base anterior. The first pair of legs is much more 
slender than the second and third which are stout and terminated by 
powerful claws fitted for clasping the hairs. The female measures about 
1.5 mm.; the male about 1 mm. in length. It infests the hairs of the 
pubic region and of the armpits, rarely passing to other parts. 

Of these three species Pediculus humanus is the most widely dis- 
tributed. 

Pediculosis, Control and Treatment 

Contagion in pediculosis is due to the rapid succession of generations 
of lice, their passage from host to host being facilitated by close associa- 
tion, grooming utensils, blankets, harness, bedding, etc. It is possible 
for domestic animals of different species to infect each other. Such 
migrations, however, are usually of an accidental nature, and the 
parasites will not as a rule remain to nuiltiply upon a host foreign to 
them. 

Long hair, especially if combined with unclean conditions, predis- 
poses to lousiness. If in addition thei'e is debilitj^ the etiologic factors 
become ideal. Plenty of nutritive food and a thorough cleaning up of 
animals and their surroundings are, therefore, essential to success, what- 
ever measures of eradication may lie applied. 

After the removal and burning of litter the stables, kennels, etc., may 
be treated with boiling water and afterward whitewashed or washed with 
a three to five pw' cent, creolin solution. For spraying interiors an 
emulsion of kerosene (formuLT, page 48), or the lime-sulphur prepara- 
tion (page 125) may he used. 

Clipping of long-haired animals, which may include the horse and 
ox, greatly simplifies their treatment. The Melophagus infesting sheep 
is removed with the fleece at time of shearing, the anhnal soon ridding 
itself of any which may have remained upon the skin. 

Among the considerable number of insecticide agents used upon the 
bodies of infested animals but one or two of those most effectual and 
most commonly employed need be mentioned here. A decoction of 
tobacco, one ounce to the quart of water, as a local apphcation answers 
well for all animals. In using this preparation the possibility of nicotine 
poisoning should he kept in mind. Large areas of the body should not 
be dressed at the same time. 

Horses may be treated with creohn two to three per cent., or kerosene 
emulsion. Brushes and combs, after having been disinfected by scald- 
ing, may have a little kerosene sprinkled ujion them as they are used. 
Preparations of kerosene should not he applied to sweating animals or 
while they are exposed to hot sunshine. Friction with fatty substances, 



J 



THE LICE 81 

as linseed oil, will kill bj^ asphyxia lice with which it comes in contact. 
This treatment is more effectual if kerosene be shaken up with the oil 
in the proportion of one of the former to two of the latter. A mixture of 
kerosene, sulphur, and lard, equal parts, is also quite useful for this pur- 
pose. 

These treatments will apply to cattle as well as to horses. Where 
large numbers of cattle are affected resort must be had to spraying with 
kerosene emulsion or dipping. For the latter purpose ordinary sheep 
dip or a lime-and-sulphur preparation may be used. 

The large sucking louse of the hog is found principally inside, behind, 
and in front of the ears, on the breast, and on the inner side of the el- 
bows. For this animal the stronger preparations of the insecticides 
should be used, as creolin five per cent, or kerosene and oil equal pai'ts. 
The kerosene, sulphur, and lard mixture is quite a suitable one for these 
animals. It is well also to treat their wallows with a three to five per 
cent, solution of creolin. 

For dogs creolin in two per cent, strength is quite satisfactory. Long- 
haired dogs, especially if heavily infested, should be clipped before 
treatment. For small house anunals, as toy dogs and cats, pyrethrum 
powder, applied to the moistened skin as for fleas, is most suitable. 

Whatever insecticide is used it is well to apply vinegar in conjunction 
with it. This may be added to the fluid preparations in the proportion of 
about ten ounces to the quart, or it maj^ be applied separately diluted 
with twice its quantity of water. The vinegar has a destructive action 
upon the eggs which may survive the ordinary remedies used to destroj^ 
the insects. 

Sodium fluoride, which is recommended in the treatment of lice of 
poultry, all of which are biting lice, should also be effective for the biting 
lice of mammals, though experience'with it up to the present time is not 
sufficient to have established its value in such cases. In its application 
it should be rubbed into the hair over all parts of the bodJ^ The treat- 
ment is only apphcable to biting Uce. 

All measures used for the eradication of lice, whether in the quarters 
or upon the bodies of their hosts, should be repeated at least three times 
at intervals of eight to ten days. This is necessary to destroy the hce 
which may emerge from remaining eggs. 



CHAPTER IX 

LICE OF POULTRY. THE BEDBUG 

Birds under the usual conditions of domestication are especially 
prone to lousiness; there are, in fact, few fowls entirely free from them. 
Though, relative to their mimbers, lice upon poultry probably do less 
harm than the blooil-sucking ticks, their rapiil nuiltiplication, and the 
fact that they ]3ass their entire cycle upon the bodies of their hosts, 
make it prol)able that any degree of infestation will become a destruc- 
tive nuisance. The constant annoyance due to their crawhng upon 
the skin and among the feathers, with the energy expended in the efforts 
to be rid of them, causes fowl to droop and become ready victims to other 
diseases commonly affecting poultry. Flesh and egg production, under 
such conditions, nmst essentially be retarded to a degree commensurate 
to the infestation. 

Young chicks are especially apt to succumb. They give evidence of 
the presence of lice by drowsiness, refusal to eat, and an emaciated 
body. The symptoms are generally accompanied by a loss of feathers, 
especially about the head and lower part of the neck. Chickens hatched 
in an incui)ator should be free from them, and they will remain so unless 
placed with a lousy hen or put in infested quarters. 

The head and upper part of the neck afford a protective location for 
the lice, as they cannot here be reached by the beak. They ma.v, how- 
ever, especially in older birds, be found upon all parts of the body. 

The biting species with which birds are infested belong with either the 
Philopterida' or Liotlxuda^, the former containing species harbored by 
both mammals and birds, the latter lice of birds only. 

Lice of Chickens 

The Philopterida' of chickens are Goniocotes gallina', (i. (jicjas, Lipeurus 
caponis, and L. heteroyraphus. 

1. Goniocotes galliiue (G. hologaster). — Head broad as long; anterior 
border rounded ; angulai' at temjiles. Abdomen sac-like in outline, hav- 
ing curved l)ands upon lateral borders of segments; transverse patches 
in double row. General color dirty yellow. Female about 1 mm. in 
length. 

A coimnon species. 

2. Goniocotes gigas (G. abdominalis) . — Head rounded, circular in 
front. Thorax narrow. Abdomen large and but slightly longer than 



LICE OF POULTRY. THE BEDBUG 



83 



broad; each segment marked laterally by long tongue-shaped spots. 
The general color is yellowish. The female is 3 to 3.5 mm. in length, a 
size exceptional in this genus (Fig. 49). 

About as common as the preceding species. 

3. Lipeurus caponis (L. variabilis). — In all members of this genus the 
body is elongated and narrow. Head longer than broad and rounded in 
front. Abdomen long and slender with black margins. Color yellowish 
white. Female about 2 mm. in length (Fig. 50). 

By its long and slender appearance this species can easily be dis- 
tinguished from others infesting the chicken. It is not very common. 

4. Lipeurus heterographus. — Head more narrow in front and body 
much stouter than m preceding species. Abdomen elongated oval in 






Fig. 49.— Gonio- 
cotes abdominalis 
(after Osborn, from 
Denny, Bui. No. 5, 
Bureau of Entomol- 
ogv, U. S. Dept., of 
Agi-.). 



Fig. 50. — Lipeu- 
rus variabilis (after 
Osborn, from 
Denny, Bui. No. 5, 
Bureau of Entomol- 
ogy, U. S. Dept. of 
Agr.). 



Fig. 51. — Menopon 
pallidum (after Os- 
born, from Denny, 
Bui. No. 5, Bureau 
of Entomology, U. 
S. Dept. of Agr.). 



outline with median spots on each ring. General color pale yellow. 
Female 2 mm. in length. 

This species has not been often observed in this country. It is said 
to also occur upon certain species of pheasants. 

Of the Liotheidffi chickens are hosts to two species, Menopum trig- 
onocephalun and M. biserialum. 

5. Menopum trigoiwcephalum {M. pallidum; Menopon pallidum). — 
Head somewhat triangular, rounded in front and at the temples. Abdo- 
men of female elongated oval in outline, in male longer and narrower. 
Legs stout and hairy. Color light yellow. Female about 1.5 mm. in 
length (Fig. 51). 

This is the most prevalent of all of the hen lice. It is an active runner 
and passes readily to other species of birds. 

6. Menopum biseriaium {Menopon biserialum). — Head somewhat 
crescent-shaped. Legs stout. Abdomen elongate. Has the same gen- 



84 PARASITES OF THE DOMESTIC ANIMALS 

eral color as M. tn'gonocephaluni, but is larger. Female about 2.5 mm. in 
length (Fig. 54). 

Less common than preceding species. It attacks young chicks, espe- 
ciallj' about the head and anus. It niaj'- also be found upon turkej^s and 
peafowl. 

Lice of Txjrkeys 

The Philopteritloe of turkeys are Goniodes stylifer and Lipeunis 
meleagridis. 

1. Goniodes stylifer. — Head broad as long, well rounded in front, with 
posterior angles projected backward into points which are terminated by 
strong bristles. Thorax angular and narrowed anteriorl3^ Legs slender 
and hairy. Abdomen broad, with tongue-shaped bands on the sides. 
Hairs are numerous and long on both surfaces. Color yellowish white. 
Female about 3 mm. in length (Fig. 52). 

This is a large species couunon upon turkeys everywhere. 

2. Lipcurus tneleagridis (L. polylrapezius) . — Head longer than broad, 
rounded in front and at the temples. Thorax and abdomen narrow and 
elongate; last alxlominal segment in female deeplj' notched. Color pale 
yellow. Female about 2.8 nun. in length (Fig. 53). 

Also quite common. 

The Menopum of the turkej- is M. hiseriatiim (Fig. 54), referred to 
under the Liotheidse of chickens. 

Lice of Ducks and Geese 

Of the Philopteridse ducks and geese harbor two species, Philopterus 
iderodes and Lipeunis anatis. 

1. Philoplerus iderodes (Docophonis iderodes). — Head longer than 
broad, rounded in front; lower portion expanded and rounded. Abdo- 
men oval in outline, white in center, and with dark lateral bands. Color 
brownish red. Female 1 mm. in length. 

Of conmion occurrence. 

2. Lipeurus anatis {L. squalidus). — Head longer than broad, cone- 
shaped, rounded in front. Thorax and abdomen elongate with dark 
borders. On the abdomen the border is broken into patches correspond- 
ing with the segments. General color light yellow. Female about 4 mm. 
in length (Fig. 55). 

Frequently found upon both domestic and wild ducks. 
The Liotheidffi of ducks and geese are Trinotum luridum and T. 
lituratum. 

3. Trinotum luridum (Trinoton luridum). — Head as wide as long, 
somewhat triangular in shape, with rounded corners. Thorax longer 
than head. Abdomen long and narrow, with dark bands upon the 



LICE OF POULTRY. THE BEDBUG 



85 




Fig. 52. — Goniodes stylifer 
(after Osborn, Bui. No. 5, Bu- 
reau of Entomology, U. 1.S 
Dept. of Agr.). 





Fig. 53. — Lipeurus polytrapezius 
(after Osborn, from Piaget, Bui. No. 5, 
Bureau of Entomology, U. S. Dept. of 
Agr.). 




Fig. 54. — Menopon biseriatum (after 
Osborn, Bui. No. 5, Bureau of Entomol- 
ogy, U. S. Dept. of Agr.). 



Fig. 55. — Lipeu- 
rus squalidus (after 
Osborn, Bui. No. 5, 
Bureau of Entomol- 
ogy, U. S. Dept. of 
Agr.). 



86 PARASITES OF THE DOMESTIC ANIMALS 

segments. Entire insect long and narrow. General color grayish. 
Female 4 mm. in length (Fig. 56). 

A common species. 

4. Trinotum lituratum {Trinoton lituratum). — Shorter and smaller 
than the preceding species, with head, thorax, and abdomen relatively 
broader. Legs bi-oad and stout. Abdominal segments bordered by 
darkened spots. Color white. 

This species occurs upon domestic geese. 

Lice of Swan 

Philopterus cygni and Oniithonomus cygni are species of Philopteridae 
harbored by swan. 

1. Philopterus cygni (Docophurus cygni). — Head about as broad as 
long, rounded in front. Thorax short and narrow. Abdomen sacular, 
white in center, darkened at sides. Head, thorax, and legs reddish 
brown. Female 1 mm. in length (Fig. 57). 

This is the "Little Red Swan Lou.se." It is quite common. 

2. Ornithonomus cygni {Ornithohius bucephalus; 0. cygni). — Head 
massive and nearly as broad as long. Thorax about the same length as 
head. Abdomen narrow oval, tapermg toward apex; black points on 
outer nuirgins of four of the abdominal segments. The body is trans- 
parent and much flattened. General color white. Female 4 mm. in 
length (Fig. 58). 

Occurs in gieat abundance on all species of swan. 

Lice of Pigeons 

The more common Philopteridae of pigeons are Goniocotes compar, 
Goniodes damicornis, and Lipeurus columbce. 

1. Goniocote.s compar. — Head large, nearly as broad as long, rouufied 
in front. Thorax narrow. Abdomen broad oval. Color dirty j'ellow. 
Female about l.'.i mm. in length (Fig. 59). 

Found quite frequently. 

2. Goniodes damicornis. — Head about as broad as long, rounded in 
front, angular behind. Legs stout. Abdomen broad and short. Color 
brown. Female 2 nun. in length (Fig. 60). 

Not as conunon as preceding species. 

3. Lipeurus columbce (L. baculus). — Characterized bj' its extreme 
slenderness. Head long and narrow, as is also the thorax and abdomen. 
Upon the abdominal segments are brownish patches. Head and thorax 
brownish red in color; abdomen dusky. The female is 2 mm. in length. 

Occurs abundanth-. 



LICE OF POULTRY. THE BEDBUG 



87 




Fig. 56.— Trino- 
ton luridum (after 
Osborn, Bui. No. 5, 
Bureau of Entomol- 
ogy, U. S. Dept. of 
Agr.). 




Fig. 57. — Docophorus 
eygni (after Osborn, Bui. 
No. 5, Bureau of Ento- 
mology, U. S. Dept. of 
Agr.). 




Fig. 5S. — Ornithobius cygni 
(after Osborn, Bui. No. 5, Bureau 
of Entomology, U. S. Dept. of 
Agr.). 




Fig. 59. — Goniocotes com- 
par (after Osborn, Bui. No. 5, 
Bureau of Entomology, U. S. 
Dept. of Agr.). 




Fig. 60. — Goniodes dam- 
ieornis (after Osborn, Bui. 
No. 5, Bureau of Entomol- 
ogy. U. S. Dept. of AgT.). 



PARASITES OF THE DOMESTIC ANIIVMLS 



Control and Treatment 

In dealing with lice of poultry we should first discriminate between 
the lice and the ticks, bearing in mind that the latter do not breed upon 
their hosts. According to whether they be one or the other the treatment 
will be modified somewhat, though certain measures of eradication maj' 
be suitable for either. All species of lice, without a known exception, 
passing their transformation upon the host, there may be confidence in 
attacking them that there are no eggs and young developing in some 
out-of-the-way retreat, as in the case of ticks or bedbugs. 

As a means of controlling bird lice the dust bath should receive first 
attention. The fine dust particles enter the spiracles of the insects, 
killing them by suffocation, therefore, of whatever material it may con- 
sist, the dust will be most effectual when fine and penetrating. Road 
dust is usually quite suitable; it will be the more efficient if powdered 
tobacco be added in the proportion of about one of tobacco to five of 
dust. Fine ashes, in which powdered sulphur is mixed, make an ex- 
cellent dust wallow. A mixture of road and lime dust, with the addition 
of a cupful or two of sulphur, maj' be used with as good results. The 
dust baths should be in deep and roomy boxes placed where they will be 
sheltered from the rain. 

As an insecticide for the individual treatment of badly infested birds, 
any oleaginous substance is effectual. As with dust, the principle upon 
which its use is based is that of suffocation, the unctuous agent serving 
to plug the liieathing pores of the insect. A mixture of lard and sulphur 
answers well for all birds. It should especially be applied at the throat, 
upper neck, bases of the wings, and at the base of the tail feathers. If a 
powder is used, as pyrethrum, the skin should be first moistened with 
soapy water or equal parts of glycerin and water and the powder then 
blown well under and through the feathers. 

Investigations by the United States Bureau of Entomology with 
sodium fluoride have demonstrated that lice infesting poultry may be 
readily dcstroj-ed by the application of a small quantity of this powder. 
It may be used iji the powdered form or as a dip. Applied by the former 
method, it should be sprinkled under the feathers of the neck, breast, 
back, tail, below the vent, and upon the imder side of each wing as these 
are spread. If used as a dip, this may be prepared by adding one ounce 
of commercial sodium fluoiide to the gallon of water. The solution 
should be made tepid and the entire body of the fowl, excepting the 
head, immersed in it. For the treatment of one hundred fowl, about one 
pound of the powder will be required. 

As the lice are likely to be dislodged from their hosts to be harbored 
for a time about nests, roosts, etc., it is essential that the eradicative 
measures be also applied to the quarters of infested birds. The louse 



LICE OF POULTRY. THE BEDBUG 89 

'most commonly found upon the hen, Menopuni trigonocephahmi, is an 
especially active runner, readily passing to other species of birds or to 
any object with which the infested animal is in contact. It is said that 
horses kept in the vicinity of chicken houses harboring this louse are 
often seriously troubled by it. 

In this connection the measures recommended for the eradication of 
the lice of manmials and poultry-infesting bedbugs will in general 
apply here. All nesting material and litter must, of course, be cleared 
out and burned or buried. A washing down with five per cent, creolin 
or carbolic acid solution should follow, the usual whitewashing in such 
cases adding to the probability of a complete destruction of the lice. 
The lime and sulphur mixture (page 125), applied as a spray to all parts 
of the interior, is penetrating and gives satisfactory results. 

As a simple agent for the killing of lice or mites in the hen house and 
dovecot the cloud of lime dust is said to be of much value. In the appli- 
cation of this method the birds should be absent and the quarters closed. 
A few handfuls of finely powdered lime are then thrown against the roof 
and walls, producing a cloud of dust. This will settle upon the roosts, 
nest compartments, and floor, and into the crevices, destroying many of 
the exposed vermin. Afterward the place should be swept out and the 
sweepings buried, burned, or otherwise destroyed. 

Fumigation is commonly resorted to, and may have value as a con- 
tributory measure. The sulphur fumigation, applied as recommended in 
the eradication of bedbugs, will serve here as well. 

Observations made as to the length of time required for the hatching 
of the eggs, while not complete, indicate that for species of bird lice in 
general, five to six days are necessary at least. Therefore, in repeating 
treatments intended to kill individuals hatched from remaining eggs, 
there should be an intervening period of about ten days. 

Order V. Hemiptera 

Insecta (p. 15). — This group includes the cicadas, plant Kce, and true 
bugs. The mouth parts are suctorial, the mandibles and maxillse being 
modified into bristle-Uke structures for puncturing and extracting the 
juices of plants or the blood of annuals. The labium is usually jointed 
and forms a sheath for the piercing bristles. There are usually four 
wings, some forms havmg the first pair thickened and leathery at the 
base, while only the tips are membranous and elastic. It is from this 
"half -winged" structure that the order derives its name. In some of the 
lower forms (bedbugs) wings are absent. A characteristic of the order is 
the presence of stink glands, which in the adult open ventrally on the 
metathorax. The secretion from these glands has a disgusting odor, 
jirobably originally of defensive service to the insect though in parasitic 
forms rather serving to reveal their presence and location. The meta- 



go PARASITES OF THE DOMESTIC ANIMALS 

inorphosis is incomplete, the immature insect resembling the adult ex- 
cept in the absence of wings. 

Family Cimicid^ 

Hemi])terii (p. 89). Bedbug and allies. — The body is much flat- 
tened and is ovate in outline. The adults are reddish brown in color; 
young yellowish white. When full grown they are from one-sixth to one- 
fifth of an inch in length. The mouth parts inclose long slender stylets 
(Fig. 61, d). OceUi are absent. Wing-covers rudimentary (Fig. 61, c). 

CiMEx Lectularius 

Acanlhia leduloria. The common bedbug. (Fig. 61). — Cimicidse 
(p. 90). The body is covered with short hairs; rostrum short; third 
and fourth joints of antennae much thinner than first and second; second 
segnmnt of antennae shorter than thiril. 

The eggs are oval, pearly-white, antl about a millimeter in length. 
The young leave the egg by a small opercvdiun at the end. The female 
deposits from one hundred to two hundred eggs in cracks, crevices, and 
seams of beds and bedding, beneath loose portions of wall-paper, base- 
boards, floor spaces, and similar retreats. 

Hatching occurs in about one week. Development from the n}^nphal 
to the adult stage will, under favorable conditions, occupy about six 
weeks. The time required for the development of adults from deposited 
eggs under such conditions may, therefore, be approximated at from 
seven to eight weeks. 

Habits and Effect of Bite. — In their feeding habits bedbugs are 
nocturnal, hiding in their ilarkened retreats during the day and coming 
forth at night to crawl upon the legs, anns, neck, or other improtected 
parts of their victims, where they will feed to repletion. After this en- 
gorgment the insects will retreat to their usual haunts to remain for 
several days, during which time the meal is digested'. 

The effect of the bite of the bedbug varies, depending upon the sus- 
<'ef)tibility of the one attacked. In some it produces marked irritation 
with more or less swelling ; others may not be made aware of its presence. 
The inflammation experienced by sensitive persons seems to result 
mainly from the puncture of the skin. The biting organ is like that of 
other liempiterous insects; there are four jiiercing filaments within the 
labium which is closely applied to the point of puncture as the blood is 
drawn up. 

The degree to which the insect maj' injure other animals than man is 
somewhat obscure. Probably the same or closely allied species to those 
attacking man attack animals in the same manner. Chickens are es- 



LICE OF POULTRY. THE BEDBUG 



91 




Q 






M _ 

C '^ 

M . 

C 



I ^ 



92 PARASITES OF THE DOMESTIC ANIjNIALS 

peciallj' likely to be theii' hosts, the usual quarters of poultry affordmg 
an ideal harl)or for such pests. 

Control. — Bedbugs may be easily carried upon clothing, therefore 
puljlic conveyances and places where people of all sorts and conditions 
of living may congregate, afford a common means for their dissemina- 
tion. They are highly prolific, and the introduction of a single egg- 
bearing female may be sufficient to start a colony of bedbugs within a 
few months. 

Eradication is made somewhat difficult by the parasite's habit of 
seeking hiding places during the day, therefore anything used for this 
purpose must l)e of such a nature that it will penetrate into cracks, 
crevices, joints of bedsteads, mattress seams, and all such places where 
the gregarious insects are in the habit of assemljling and depositing 
their eggs. Powders, such as pyrethum, are of practically no value as 
they are not sufficiently penetrating. One of the best remedies is kero- 
sene, applied with a feather, or, better, with an ordinary machine oiler. 
Benzene is as effectual and will volatilize more readily, but must be 
used with great caution against ignition. A solution of corrosive sub- 
lunate ill alcohol may also be used with good results. Fumigation is of 
doubtful value, though flowers of sulphur, two pounds to each one 
thousand cubic feet of room space, has been recommended for this pur- 
pose. The sulphur should be placed in a heap in a pan, a depression 
made in the top, and a small quantity of alcohol poured into this to 
facilitate burning. The container should be placed in a larger pan and 
surrounded l)j- water as a precaution against fire. During fumigation 
the room should, of course, be tightl}' closed. Fumigating with 
formaldehj'de gas is as useless against bedbugs as it is against other 
insects. 

Whatever remcd.y may be applied, thorouglmess is essential to success. 
Beds and bedding should be inspected daily, and all places where the 
bugs may have found a hiding place repeatedly treated. There will be 
less difficulty if brass and iron bedsteads are used, the old-fashioned 
wooden bedsteads furnishing many retreats into which the bugs can 
force their ffat, thin bodies. 

In infested chicken houses the parasites usually secrete themselves 
around the ends of the roosts and in the nests. Their attack upon the 
chickens at night results in a loss of flesh with reduced egg production. 
In heavy infestation chickens will often die from emaciation and loss 
of blood. If the propagation of the bugs in the chicken houses is not 
checked, they maj' spread to nearby buildings to become a source of 
annoyance to other live stock. 

Control measures in such cases consist m thoroughly renovating the 
chicken house. Roosts in wooden fittings should be taken down, and 
all loose hmiber, useless boxes, straw, or other material affording hiding 



LICE OF POULTRY. THE BEDBUG 93 

places removed and burned. Possible breeding places remaining should 
be sprayed with kerosene or kerosene emulsion (page 48). Scalding 
hot water or whitewash will destroy both the insects and the eggs. The 
kerosene application should be repeated at frequent intervals to insure 
the eradication of following generations. 



CHAPTER X 

THE MITES 

Class II. Arachnida. Arthropoda (p. 13). — The arachnids may at 
once he distinguished from the insects by the relationship of the body 
parts and the numlier of aml)ulatory appendages, as to be described. 

The regions of the body are more or less fused, the head being com- 
monly fu.sed with the thorax to form the cephalothorax (Fig. 62). 

The abdomen is in some forms segmented (scorpions), in others un- 
segmcnted and separated from the thorax by a deep construction (true 
spiders). 

Sometimes the cephalothorax and abdomen are fused into one un- 
segmented body (ticks and mites). 

In the adult there are four jDairs of locomotor appendages, usually 
seven-jointed, attached to the cei)halothorax. There are no wings. 

Antennae are absent. 

The mouth parts are paired cheliceri3e and pedipalpi, the fir.st in front 
of the mouth, the .second to the side. 

The chelicerie are short, consisting of two or three joints. The last 
joint may have a claw-like termination for piercing and introducing 
poison into prey (spiders), or it may be m the form of small chelae (scor- 
pions). 

The pedipalpi are longer and more like the appendages for locomo- 
tion. The terminal segment may l)e .strongly chelate (scorpions). 

The eyes are located anteriorly upon the cephalothorax and consist 
of a varying innnljer of ocelli. The eyes are never compound. 

The skin is of a leathery con.sistency and is not so hard as in insects. 

Resi)iration is either by tracheae or by so-called book-lungs, the latter 
consistijig of a series of invaginations of the skin closely applied like the 
leaves of a book. Either one or both of these forms of respiratory organ 
may occur in a single individual. 

Most arachnids are oviparous. In aberrant forms, as Linguatulida and 
Acarijia, certain adult ajipendages are acquired after a molt. 

The class Arachnida includes the scorpions, spiders, ticks, and mites. 

The two parasitic orders are Acarina, which includes the ticks and 
mites, and Linguatulida, containing the species Linguatula rhinaria. 

Order I. Acarina. Ticks and Mites. — Arachnida (p. 94). These are 
small, frequently microscopic, arachnids in which there is generally no 
distinct demarcation between tlie ccjihalothorax and abdomen, the body 
regions l)eing massed into one. 



THE MITES 



95 



Due to parasitism, the mites have undergone considerable modifica- 
tion, the scab mites are without eyes or organs of respiration, and gener- 
ally the tips of the feet are terminated b3' suckers or bristles. 

In the larval stage, the Acarina have but three pairs of legs, the fourth 
pair appearing behind the third after a molt. 

The mouth parts are modified into a beak-like structure for piercuig 
and sucking. 

The sexes are separate and reproduction is by eggs which are extruded 
from the genital pore situated, as in other Araclinida, anteriorly on the 
ventral surface of the abdomen. In the scab mites (Sarcoptidse) the fe- 
males are provided with a second genital opening, the copulating vagina, 

G J M 
C B' 





Fig. 62. — Diagram of the anatomy of a spider; a, anus; b, cecum of 
mesenteron; b', its anterior end; b", branches' of cecum extending into 
legs: c, cerebral ganglion connected "with ventral ganglionic mass; d, 
mesenteron; e, poison glands; g, heart; h. chelicera; i, pedipalpi; j, liver; 
k, hepatic duct; 1. lung sac; m. Malpighian tubules; n, dilation of rectum 
into which Malpighian tubules open; o. eyes; ov, ovaries; p. female 
genital pore; q, large and small silk glands; r, opening of tracheal sj'stem; 
s, spinnerettes (after Boas by Kirkaldy & Pollard). 

which is located posteriorly just in front of the anus. It is at this open- 
ing that spermatozoa are received during copulation, the anterior open- 
ing serving as the pore of the oviduct. 

In their development the Acarina undergo a succession of stages. The 
larvae are usualh' provided with but three pairs of legs (hexapodal) , and 
have no definite sexual characters. After molting a fourth pair of legs 
appears, and the acanis enters upon its njanphal stage. Following 
further molting the genital organs are acquired, and it has then reached 
the pubescent stage, or stage of sexual maturity. After copulation the 
female undergoes a further transformation, becoming an egg-bearing, 
or ovigerous female. 

Parasitism. — The majority of the Acarina are parasitic, though, as 
to this habit, there is much diversity, some being semiparasitic, others 
e.ssential!y so and restricted to definite hosts. 

The order contains a number of families of which the following are 
here considered: 



96 PARASITES OF THE DOMESTIC ANIMALS 

Family I. Gamasidae. — Poultry mites. 

Family II. Trombidiidse. — Harvest mites or chiggers. 

Family III. Sarcoptidse. — Mange and scab mites. 

Family IX. Demodecidse. — Follicle mites. 

Family V. Cytoleichidae. — Deep seated mites of birds. 

Superfamily Ixodoidea. — The ticks. 

Family I. Argasidig. — The fowl tick and ear tick. 

Family II. Ixodidse. — The cattle tick and other ticks. 

Each of these contains species parasitic upon mammals or birds with 
the exception of the Demodecidse, which, so far as known, have onh- 
been found upon manuuals. 

The condition produced upon the host by the presence of parasitic 
Acarina is designated medically as acariasis. Differing in their grade 
of parasitism, the nunierous species brmg about a varying degree of 
distiu'bance to the skin which they inhabit. Accordingly there is dis- 
tinguished sarcojitic and psoroptic acariasis, the former produced by 
species which burrow and form subepidermic galleries in which thej" 
deposit their eggs, the latter by species living upon the skin's surface. 
The term mange is limited by most writers to acarises caused by species 
of the genus Sarcoptes and its near allies, or by Demodex, both living 
beneath the skin's surface, the last named in the hair follicles and se- 
baceous glands. The psoroptic form, in which there is deep scab for- 
mation, constitutes true scabies or scab, although these latter terms are 
frequently used in a general sense relative to the condition produced 
by the mange and scab mites. Acari belonging with the families Ga- 
masida», Tronitiidiidse, and the superfamily Ixodoidea do not cause 
mange or scab. 

Classification of Parasites of the Class Arachnida 

Class B. Aracluiida. P. 94. 
Order I. Acarina. P. 94. 
Family (a) Gamasidse. P. 98. 
Genus and Species: 

Dcrman.\'ssus gallinse. Host, poultry. P. 98. 
Family (b) frombidiida;. P. 99. 
Genus and Species: 

Trombidium holosericeum. Larvce attack man and lower 
animals. P. 100. 
Familj' (c) Sarcoptidse. Mange and scab mites. P. 101. 
Genus and species: 

Sarcoptes scabiei var. Equi. Host, equines. P. 104. 
S. scabiei var. Ovis. Host, sheep. P. 112. 
S. scabiei var. Bovis. Host, cattle. P. 114. 
S. scabiei var. Suis. Host, hog. P. 114. 



THE MITES 97 

S. scabiei var. Canis. Host, dog. P. 115. 
Notoedres cati var. Cati. Host, cat. P. 118. 
N. cati var. Cuniculi. Host, rabbit. P. 118. 
Psoroptes communis var. Equi. Host, equines. P. 108. 
P. communis var. Ovis. Host, sheep. P. 109. 
P. communis var. Bovis. Host, cattle. P. 113. 
P. communis var. Cuniculi. Host, rabbit. P. 118. 
Chorioptes commimis var. Equi. Host, equines. P. 108. 
C. commmiis var. Ovis. Host, sheep. P. 112. 

C. communis var. Bovis. Host, cattle. P. 113. 
Otodectes cynotis var. Canis. Host, dog. P. 117. 

0. cynotis var. Cati. Host, cat. P. 117. 
Cnemidocoptes mutans. Host, poultry. P. 132. 
Cn. gaUinse. Host, poultry. P. 133. 

Famih^ (d) Demodecidse. Follicular mange mites. P. 103. 
Genus and Species: 
Demodex folliculorum var. Ovis. Host, sheep. P. 112. 

D. folliculorum var. Suis. Host, hog. P. 115. 
D. folliculomm var. Canis. Host, dog. P. 116. 

Family (e) Cytoleicliidae. P. 134. 
Genus and Species: 

Cylioleichus nudus. Host, poultr.y. P. 134. 
Laminosioptes cysticola. Host, poultry. P. 134. 
Superfamily Ixodoidea. Ticks. P. 139. 
Famil3r (a) Argasidae. P. 139. 
Genus and Species: 
Argas miniatus. Host, poultr3'. P. 139. 
Otobius megnini. Hosts, equines, cattle, etc. P. 140. 
Family (bj IxodidiB. P. 141. • 
Genus and Species: 

Ixodes ricinus. Hosts, cattle, equines, dog, etc. P. 143. 

1. he.xagonus. Hosts, cattle, dog, etc. P. 143. 
Dermacentor variabilis. Hosts, cattle, dog, equines, etc. 

P. 143. 
D. reticulatus. Hosts, cattle, equines, etc. P. 143. 
Margaropus annulatus. Hosts, cattle, equines. P. 144. 
Amblyonuna americanum. Hosts, cattle, dogs, equines, etc. 
■ P. i45. 
Order 2. Linguatulida. P. 153. 
Family (a) Linguatulidse. P. 153. 
Genus and Species: 
Linguatula rhinaria. Host, dog. P. 153. 



98 



PARASITES OF THE DOMESTIC ANIMALS 



Family I. Gamasid^ 

Acaruia (p. 94). — The gaiiiasid mites. The mouth parts are ar- 
ranged for piercing and sucking, maxillae fused into a tube, maxillary 
palps five-segmented and provided inwardly with secondary palps. 
The legs have six segments, the tarsi terminating by two booklets. 
There are two stigmata located near the insertion of the posterior legs. 
The cephalothorax ami abdomen are fused into one body. The integu- 
ment is of a leatheiv textiu'e. Eves are absent. 



Dermanyssu.s GaLLINvE 

Poultry mite; chicken "tick" (Fig. 63). Gamasidae (p.' 98).— Body 
somewhat egg-shaped with larger end posterior, slightly flattened from 
above to below. The lower half of the body is provided with short. 




Fig. 63. — Dernianyssus gallinae: a, adult; b, tarsus; c, mouth- 
parts; d and e, young — all enlarged (after Osborn, Bull. No. 5, Bureau 
of Entomology, U. S. Dept. of Agr.). 

well-separated bristles. The color is light gray with dark patches 
showing thi'ough the skin; when engorged with blood the color is a 
distinct led. The ovigerous female is rather less than 1 mm. in length. 

Occurrence and Habits. — The little poultry mite, found everywhere 
where chickens are kept, is one of the most persistent and injurious pests 
that the poultry raiser has to contend with. Remaining in darkened 
retreats about the henhouse during the daytime, these acari come forth 
at night to swarm upon the fowls and suck their blood. Their attack, 
however, is not confined entirely to the night, and hens may be driven 



THE MITES 99 

from their nests by the activity of the pests which the warmth of their 
bodies creates. 

The Demianyssus does not hmit itself to birds, but may attack 
mammals, including man, though these animals, being accidental hosts, 
the invasion is usually limited in its extent and duration. Horses kept 
in the vicinity of infested henhouses are likely to be tormented by the 
mites, the litter about stables so located affording a harbor to which 
they readily migrate. 

The eggs are deposited in vast numbers in the daytime retreats. 
Under ordinary conditions about five days are required for the hatching 
of the hexapodal larvae which do not wait for maturity to attack the 
chickens. They may, however, remain for months without a host upon 
which to satisfy their appetite for blood. Extremely prolific, they 
especially thrive upon filth, and large colonies may be found wherever 
such material has collected. 

Effect. — Fowls suffer not only from the extreme irritation and an- 
noyance of the attack, but additionally from the extraction of a consider- 
able amount of blood. Prolonged infestation must essentially bring 
about a progressive emaciation and weakening which may end in death, 
young chicks especially being likely to succumb. In any event egg 
production is retarded, and the chickens, in their unthrifty condition, 
are unprofitable for marketing. 

Control. — Cleanliness and plenty of sunlight are especially antago- 
istic to the Dermanyssus. The cleaning up measures set forth elsewhere 
for the eradication of the parasites of the henhouse need not be repeated! 
here. Kerosene emulsion (page 48) is serviceable, but should only be 
applied after the entire interior has been stripped to the boards of every- 
thing movable and all crevices, joints, and roost insertions exposed. 
It is well to drench cracks and the ends of roosts with pure kerosene or 
scalding water. The ends of roosts, before being replaced, should be 
dipped in coal tar, and this spread along the roosts for about six or eight 
inches from their supports in such manner that the mites will be obliged 
to cross the tar before reaching the fowls. Pyrethrum powder, alone or 
mixed with lime dust, should be shaken through the fresh nesting mate- 
rial. The dust bath, as recommended in the treatment for lice, should 
always be accessible. 

In order to insure continued freedom from the vermin it is necessary 
that the control measures be repeated at least three times at intervals 
of about ten days. 

Family II. Trombidiid.e 

Harvest mites; chiggers, or red bugs. Acarina (p. 9-i). — The body is 
red in color and covered with bristles or fine hairs. The mandibles are 
chelate; palpi prominent. The legs have six to seven segments pro- 



100 PARASITES OF THE DOINIESTIC ANIMALS 

vided with bristles or fine hairs, the tarsi terminating in two hooklets. 
Respiration is by tracheie. There are two eyes, one located upon each 
side of the cephalothorax. 

Trombidium Holosericeum 

Trombidiidae (p. 99). — -Body red and nearly square; shghtly narrower 
posteriori}' where the terminal border is slightlj- concaved; body and 
legs covered with bristly hairs. Eyes pedimculated. About 1 mm. in 
lengtli. 

Habits and Effect. — In the adult stage the Trombidium is free- 
living, feeding upon the juices of plants and small insects. It is onlj^ 
parasitic in its larval condition, in which stage it will inhabit insects 
and attack warm-blooded anmials as well. Living in the tall grass and 
upon the imder side of the leaves of weeds, they are brushed off upon 
the hands or clothing of people and upon the bodies of animals as they 
pass through the vegetation. They then proceed to burrow into the 
skin, setting up a most exasperating itching with the formation of 
reddened patches often covering considerable areas. This phase of 
the mite's parasitism is pecuhar in that it invariably perishes in the act 
of enteiing the skin. It is likelj' to be most troublesome during the late 
summer and autumn, the name Leptus aulumnalis, under which the 
larval stage of the mite has been described, being derived from this fact. 

Man is most often attacked about the lower parts of the legs and upon 
the hands. Among domestic animals, those which frequent locations 
densely covered with vegetation are the most likely to suffer. Hunting 
dogs especially are exposed, and on returning from the field will often 
exhibit sjnnptoms of great itching about the face, paws, inner thighs, 
and lielly, the parts most often attacked. Horses will be affected prin- 
cipally below the knees and hocks. 

Treatment. — As the larval mites die upon entering the skin, the 
source of the irritation is soon eluninated and the intense itching will 
usuall.y rapidly subside, leaving areas of epithelial exfoliation over the 
parts affected. Recently exposed animals will be relieved somewhat by 
frictions with a cloth sprinkled with benzene, or by the application of a 
mixture of equal parts of lime-water and Unseed oil, or sulphur ointment 
may be used. Sponging with a solution of carbolic acid at about three 
per cent, strength in water to which a little glycerin has been added, 
■will do much toward reUeving the itchmg. Ammonia-water, or a solu- 
tion of bicarbonate of soda are both of value for this purpose. 

Persons working or passing through infested districts will, in con- 
siderable degree at least, be protected from attack by applying a mix- 
ture of kerosene and glycerin to the hands and ankles. 



THE MITES 101 

Family III. Sabcoptid^ 

Mange, scab, or itch mites. Acarina (p. 94). — The body has the 
cephalothorax and abdomen fused ; it is white or reddish in color. The 
cuticular surface is transversely striated and provided with bristles, 
sometimes with short dorsal spines. The mouth parts are beak-like, 
extending forward, and covered by the protruding labrum; cheUcerse 
scissors-hke; maxillary palpi small and three-segmented. The legs are 
short and stout, have five segments, and are disposed in two groups of 
two pairs each, the anterior pairs, usually the larger and near the mouth 
parts, the posterior pairs near the abdomen. The tarsi commonly ter- 
minate in one or two booklets; they may tenninate in a long bristle or 
an ambulatory sucker, often upon a stalk which may be segTnented. 
Respiratory organs are absent; respiration cutaneous. There are no 
eyes. All are scarcely visible without the aid of magnification. 

There are frequently well-marked sexual differences. Males are con- 
siderably smaller than the females. In some males the fourth pair of 
legs is very small, and there may be plate-like copulatory suckers at 
the base of the abdomen with abdominal prolongations. As to the 
presence or absence of bristles or stalked suckers, the tarsi may ter- 
minate differently in the two sexes. 

Development. — As already stated in the general reference to the 
iVcarina, the Sarcoptidse have three distinct stages in the development of 
the male, four in the female. After sexual maturity and fertilization of 
the female, the male usually dies. Following fertiUzation the female 
molts and enters upon her fourth or ovigerous stage, — the egg-bearing 
stage, recognizable by the presence of the genital pore upon the anterior 
ventral surface of the abdomen, through which the eggs are extruded. 

The rapidity with which these acari breed is verj^ great. It has been 
estimated that one female sarcopt will produce in a subepidennic galleiy 
about fifteen individuals, from which, after ninety da3^s, there may be 
1,500,000 descendants constituting the sixth generation. 

The family includes a number of genera differing in their mode of 
attack and location upon the host. All are permanently parasitic. Of 
these, six, namel.y: Sarcoptes, Psoroptes, Chorioptes, Notoedres, Cnem- 
idocoptes, and Otodectes are considered here. The characteristics and 
habits of the principal genera met with follow. 

Sarcoptes (Fig. 64). Sarcoptidse (p. 101). — The body is rounded or 
slightly oval ; the mouth parts short and about as broad as long. Upon 
the dorsal surface of the body are a number of cone-like prominences 
and twenty spines, the latter short, thick, and grouped as follows: four- 
teen upon the abdomen, seven to the right and seven to the left side; 
six upon the cephalothorax, three to the right and three to the left. 
The legs are thick and conical, the posterior pair lieing nearly or quite 



102 PARASITES OF THE DOMESTIC ANIMALS 

<'oncealed beneath the abdominal margin when the acarus is in dorsal 
view. In the female the first two pairs of legs are termuiated by stalked 
ambulatory suckers; the posterior pairs bj' bristles. In the male all 
of the legs are provided with stalked suckers but the third pair which 
terminates in bristles. The anus is located upon the posterior dorsal 
margin of the abdomen. Just anterior to this in the female is the copu- 
lating vagina (receptaculum seminis). Upon the ventral side at the 
median anterior border of the abdomen of the ovigerous female is the 
genital pore. The males have no copulatorj- suckers or alidominal e.x- 
tensions. 

The Saicoptes live upon man and practically all of the domestic 
manunals. In the latter annuals they seek the parts of the body where 
the hair is short, while in man their preference is for places where the 
skin is thiji, as aljout the knuckles, between the fingers, and in the bend 
of the elbows and knees. A peculiarity of their attack is the habit in 
the female of cutting timnels Vjeneath the epidermis, in the bottom of 
which she deposits her eggs (Fig. (55), a circumstance that renders this 
form of acariasis relatively difficult to cure. 

The Sarcoptes inhabiting the skin of various animals cannot be said 
t o exhibit differences of specific importance. They may, therefore, be 
placet! in a single species — Sarcoptes scabiei — which may give rise to 
varieties according to host, as Sarcoptes scabiei, var. hominis of man, var. 
equi of the horse, and var. suis of swine, etc. The slight difference in 
these, as in other Sarcoptidse, is mainly one of size. 

Psoroptes (Figs. 68 and (59). Sarcoptids (p. 101).— The body is 
oval, the mouth jxirts elongated and in the form of a cone. The legs 
of the anterior pairs are thick, the posterior pairs more slender; all four 
pairs extend beyond the margin of the body. In the female the first 
two ]iairs of legs and the fourth pair are terminated by amljulatory 
suckers carried on long, three-segmented stalks, the third pair being 
terminated by bristles. The male has copulatory suckers serving for 
fixation to the female, and short posterior al)flominal prolongations 
terminated by bristles. The first three pairs of legs are terminated by 
stalked suckers; the fourth pair is stunted. 

P.soroptic scabies, the form produced by the members of this genus, 
is the most common and has been longest laiown. Unlike Sarcoptes, 
Psoroptes seek the parts of the body where the hair is long; they do not 
biu-i-ow beneath the epidermis, but attack the skin upon its surface, 
their punctures being followed by the formation of thick crusts. Under 
these they live in colonies which may coalesce and eventually cover 
areas of the body more or less circumscribed. Psoroptic scabies is most 
often observed upon animals with bodies covered wholly or ui part by 
long hair, as the sheep, ox, and horse. 

As with Sarcoptes, the difference in host inhabited by P.soroptes 



THE MITES 103 

■coincides with varieties which have unimportant and scarcely dis- 
tinguishable differences. There is, therefore, but one species, Psoroptes 
communis, designated according to host as variety ovis of the sheep, 
var. bovis of the ox, var. equi of the horse, var. cuniculi of the rabbit, 
etc. 

Chorioptes (Symbiotes; Dermatophagus) (Fig. 67). Sarcoptidse 
(p. 101). — The body is oval. The mouth parts are about as broad as 
long and somewhat dome-shaped. The legs are long and visible beyond 
the sides of the body. The ambulatory suckers are large and carried on 
short, unsegmented stalks. In the female all of the legs are terminated 
by suckers excepting the third pair, these are terminated by bristles. 
The male has copulatory suckers and abdominal prolongations ter- 
minated bj^ leaf -like processes. The fourth pair of legs is stunted; all of 
the legs are provided with suckers. 

Chorioptic mites live, as do psoroptic, in colonies upon the skin where 
the hair is long and among the crusts which they form. There is one 
species, Chorioptes communis (Symbiotes cormnunis, Chorioptes symbiotes, 
Dermatophagus communis). This infests the lower parts of the legs, 
especially of horses with long hairs upon the fetlocks, though in the ox 
this form of scabies generally has its seat at the base of the tail. 

Cnemidocoptes (Sarcoptes). Sarcoptidse (p. 101). — The body is 
rounded in outline. The mouth parts are short, broader than long, and 
rounded. In the female the legs are conical and verj^ short; they are 
without suckers or bristles, terminating in two unequal hooklets. In 
the male the legs are somewhat longer and all four pairs are terminated 
by stalked suckers and bristles. 

This genus contains a burrowing mite, Cnemidocoptes mutans (Fig. 74), 
which produces "scaly leg" in fowls; also a species loiown as the de- 
pluming mite, Cnemidocoptes gallince, which attacks the skin of fowls 
near the insertion of the feathers. 

Of the genera Notoedres (Fig. 71) and Otodectes, the former infests 
small mammals, and the latter lives in the external ear of the dog and 
cat. 

Family IV. Demodecid.e 

Acarina (p. 94). Follicular mange mites (Fig. 70). These are very 
minute and worm-like. The body is distincth' divided into cephalo- 
thorax and abdomen, the latter elongated and transversely striated. 
The anus is on the anterior ventral border of the abdomen, probably 
serving in the female for both copulation and ovulation. The legs are 
three-segmented, short and stump3^ The mouth parts are suctorial. 
Respiration is cutaneous. There are no eyes. The length is about 
0.3 mm. 

They undergo the same stages of development as other acari. 



104 



PARASITES OF THE DOMESTIC ANIMALS 



There is but one species, Demodex folliculorum (Fig. 70), which in- 
habits the hair follicles and sebaceous glands of several mammalian 
species. Its size differs somewhat with its habitat, the difference in 
dimensions authorizing a division into varieties according to host. 

Scabies of the Horse 

Horses, asses, and mules are affected with one form of mange and two 
of true scabies, as follows: 

1. Sarcoptic mange, due to Sarcopies scabiei var. equi. 

2. Psoroptic scabies, due to Psoroptes communis var. equi. 

3. Chorioptic scabies, due to Chorioptes communis var. equi. 
Sarcoptic Mange of the Horse. — In the majority of cases acariasis of 

the horse is caused by Sarcoptes (Fig. 64). It begins most frequently 




Fig. 64. — Sarcoptes scabiei var. equi, female; dorsal (left) and ventral 
(right) surface. 

about the head, sides of the neck, or at the withers, e.xtendmg, if neg- 
lected, over large areas of the body, involving in some cases even the 
lower parts of the legs. In its initial stage sarcoptic mange is somewhat 
slow in development, the small number of acari at the beginning not 
giving rise to STOiptoms readily observable. In from three to si.x weeks, 
however, the multiplication of the parasites has sufficiently progressed 
to clearly reveal the affection. 

Symptoms. — The first symptom is itching, more or less intense, 
which the animal seeks to relieve by rubbing itself against anything 
available, or by biting affected parts of the body which it can reach. 



THE MITES 



105 



When groomed with the brush or currycomb it will manifest its pleasure 
by protrusion and movements of the upper lip, at the same time leaning 
toward the brush. This action is not peculiar to mange, however, as it 
may be observed in any itching skin affection of the horse. The piiiritus 
seems to be greater at night and is always intensified by an increase in 
the warmth of the body, as by a warm stable or warm clothing. This is 
probably due to the greater activity of the parasites imder such condi- 
tions. 

Lesions. — The first changes in the skin will be the formation of 
small nodules, which may be felt bj^ the hand as it is passed over the 
skin's surface. At these locations small crasts are formed about the 
tufts of matted hairs, which are easily removed, leaving a moist and 
reddened surface. From the nodules small papules develop, the epider- 
mis being raised by the subepidermic serous effusion. These rupture, 
and the desquamated surface gradually dries, leaving a scaly formation 
upon the skin. With the extension of these lesions the hair falls out in 
patches, the affected areas becoming confluent and covered by dry 




Fig. 65. — Buitow of sarcopt in human skin, with eggs and mite (after 
Osborn, from Furstenburg and Murry; Bureau of Entomology, U. S. Dept. 
of Agr.) . 

epidermic scales and thin crusts. Soon following upon this stage the 
skin thickens and forms into folds-, especially over the parts where it is 
freely movable, as about the throat, neck and breast. When these 
folds are separated the skin between them is found to be m a raw and 
purulent condition, bleedmg at the slight touch of an instrument or 
of the finger nail. In neglected cases the body may become almost 
entirety denu(;led of hair and the thickened skin covered everj'where with 
crusts, bleeding fissures, and ulcers, the animal presenting a most 
miserable appearance (Fig. 66). The alterations in the skin are not all 
directly brought about by the parasites, being contributed to by the 
violent rubbing of the animal in its efforts to relieve the itching. Excoria- 
tions with the formation of hemorrhagic exudations and ulcers are often 
an accompaniment from this cause. 
Diagnosis and Development. — AVith these symptoms in their early 



106 PARASITES OF THE DOIMESTIC ANIMALS 

or late stages, the diagnosis of sarcoptic mange may l)e made positive 
by the recovery of the Sarcoptes. This should be looked for as soon as 
the presence of mange is suspected, as it is important to know with what 
form of the disease we have to deal. The n>'mplue and pubescent males 
and females live upon the body surface and among the crusts over all 
affected parts. Immediately after they become impregnated the oviger- 
ous females biu'row galleries beneath the epidermis in which they deposit 
their eggs and live for a time with the young larva? (Fig. 65) . In man the 
course of the galleries is marked by fine red lines from 8 to 15 mm. or 
more in length, but in the horse these cannot be seen owing to the 
thickness and pigmentation of the epidermis. The sarcopt is usually 
lodged at the extreme end of the channel in the course of which her eggs 




iffcctL'd with ad\':iric'etl sarcoptic niaiigc (.from author's photograph). 



arc distributed. It has been estimated that approximately fifteen in- 
dividuals will lie produced in each of these subepidermic burrows, and 
that about fifteen days are reciuired, under average c(mditions, for their 
full develojiment and the appearance of the next succeeding generation. 
The larva? issuing from the eggs live in the gallery for some time before 
finally making their exit along its course, while the parent female soon 
dies after ovulation is completed. Copulation takes place upon the 
skin beneath the crusts, the males dying after the performance of this 
function. As the males are also relatively less in number, it is the fe- 
males which are more often met with. 

To secure the parasite for examination the crusts should be removed 
and skin scrapings taken in such a manner as to include a portion of 
serous exudate with the epidermic scales. The material should be taken 
from a part showing evidences of recent attack, the mites being more 
likelv to be found there than in the older lesions. This material, to- 



THE MITES 107 

gether with a few flakes from the deeper portion of the crust, may then 
be placed upon a glass and teased in glj^cerin. After having been 
sufficiently divided and spread by the needles, it is readj' for examination 
under the low power of the microscope, or by a strong hand lens. It is 
often necessary to thoroughly search several preparations before finding 
the acarus. The material can be more easilj' teased and cleaned up if 
submitted for an hour or two to the action of a five to ten per cent, 
solution of caustic soda. 

A method commonly used in the Laboratoiy of the Pennsylvania 
State Bureau of Animal Industry for the detection of scab acari is as 
follows: Cover the material with a ten per cent, solution of sodium 
hydrate and set aside for one or two hours. Heat to boilmg and cen- 
trifuge for twenty minutes. The liquid is then carefulty drawn off, 
water' added, and the sediment shaken up. This is again centrifuged, 
water drawn off, and fresh water added in which the sediment is again 
washed and centrifuged. The sediment is then thmh^ spread upon 
slides and examined imder low power. By this treatment the scabs and 
crusts are thoroughly disintegrated. Some of the mites may also be 
fragmental, but not to such an extent as to prevent recognition of the 
species. 

Prognosis. — Owing to its great contagiousness and the difficult}^ in 
reaching the parasites, sarcoptic acariasis is the most serious of the 
three forms which may affect the horse. Early m its course the con- 
stantly tortured and unpresentable animal becomes mifit for work, and, 
when the disease is advanced, the skin lesions are accompanied bj' 
anaemia, emaciation, and a general debility that may terminate in death. 
As in other parasitic skin diseases, vigorous animals in good condition 
are more resistant and are more easily cured than those unthrifty or old 
and emaciated. 

Transmission. — The transmission of mange from horse to horse or 
to asses and mules takes place by contact of individuals and by numerous 
waj^s in which the parasite can be transported, as by litter, grooming 
utensils, harness, clothing, or any object upon which the affected animal 
has rubbed. Its contagion is modified considerably in relation to the 
stage of the disease. Early in its course the acari have little tendency 
to leave their host, but after one or two generations, with the formation 
of the typical i^kin lesions, they emigrate readily, either directly or in- 
directl3% from one animal to another. 

Mange of the horse can be transmitted to man and, reciprocally, 
that of man to the horse, though such cases are rare. In either event the 
parasite does not find a favorable soil for its multiplication, and the 
iii\-asion is but transient, such affection as it produces usually yielding 
promptly to treatment or spontaneously disappearing in a few weeks. 
It is doulitful whether this mange can be communicated to other animals; 



108 PARASITES OF THE DOMESTIC ANIMALS 

varieties of the sarcopt accidental!}' conveyed from their natural to a 
foreign species of host meet with an unfavorable habitat and, if cutaneous 
manifestations follow, it may be assumed that they must in any case be 
sliftht and of relatively short duration. 

Psoroptic Scabies of the Horse. — Psoroptic scabies generally appears 
about the regions of the longest hair, as at the base of the forelock, mane, 
and tail. It at once gives rise to pruritus, which is accompanied by 
rubbing and matting of the hairs as in mange, with which form it is 
somewhat sunilar as to its course and alterations. It spreads much 
more slowly, however, and rarely involves the whole surface of the 
body. 

The jjsoropt does not burrow beneath the skin's surface as does the 
sai'copt, therefore it can be more easily found. The methods recom- 
mended for securing the Sarcoptes will apply to the Psoroptes as well, 
though to obtain the latter it is not necessary to go quite as deeply for 
the material. In this connection it should be borne in mind that two 
or all three forms of scabies may coexist on the horse. It is advisable, 
therefore, in certain cases to look for the mite in material obtained from 
various affected regions of the body, as from the base of the mane, fore- 
lock, or tail, fiom the cheeks and l)reast, and from the lower parts of the 
legs. 

Lesions. — While the local alterations in psoroptic scabies are severe, 
the pniritus intense, and the scabs generally' thicker than in the sarcop- 
tic form, it is a less serious affection in that the mites do not burrow, 
and the lesions remam nmch longer localized. More easily and promptly 
cured, it is not so frequently epizootic, and it is not as likely to spread to 
other horses upon the same premises. 

Transmission. — As to its transmissibility from the equine species to 
other animals, what has been said relative to this of the Sarcoptes 
applies also to the Psoroptes. 

Chorioptic Scabies of the Horse. — This form of scabies begins on 
the e.\tremities, most often the hind feet about the fetlocks and pasterns. 
From here it spreads to the hocks, or to the knees if from the fore feet, 
sometimes extending further, but rarely as far as the bodJ^ Like the 
psoroptes, these mites seek the parts covered by long hair, therefore 
hoises with long fetlocks are predisposed to attack. 

Symptoms. — The first symptom of the invasion is itching, which 
the horse manifests by stamping, kicking the side of the stall, efforts to 
bite the legs, or rubbing them one against the other. This irritation 
is especially noticeable upon the animal's return from work and at night 
in a warm stable. Its true cause is frequently overlooked ui considering 
it a vicious habit. 

Chorioptic scabies is slow in development, and is most troublesome in 
winter. This is probably due to the fact that the feet of horses at this 



THE MITES 



109 



time of the year are more exposed to mud and slush, brmging about a 
macerated and inflammatory condition of the sldn that favors the 
multiplication of the mites. 

Lesions.^Shortly after the invasion an abundant epidermic des- 
quamation is noticed among the hairs and over the skin. Tufts of 
hair are easily pulled out, and patches appear where the skin is bare and 
smooth. Later ciiists form over a thickened and exuding skua, which 
in the hollow of the pastern becomes fissured and bleeding. 

Diagnosis. — In view of the special seat of chorioptic scabies, other 
parts not being involved, it is scarcely nec- 
essary to confirm its differentiation from 
other forms by the recoveiy of the mite. It 
is important, however, to know whether 
the case is truly one of scabies, and this 
diagnosis can only be established with cer- 
tainty by finding the parasite. If present 
it will be easily found among the deeper 
parts of the crusts and epidermic scales. 

Prognosis and Transmission. — Foot 
scab is less infectious and is accompanied 
by less itching than the other forms. The 
prognosis is also more favorable, since, ex- 
ceptmg ia rare cases, the disease is confined ■ 
to the lower parts of the legs and usually 
to the hind legs only. Again, unlike other 
scabies, it has Uttle if any general effect 
upon the anuBal. It yields readily to suit- 
able treatment, and it is not likely that 
horses receiving proper care as to cleanU- 
ness of the hair and skin will be attacked, 
even though exposed to the infection. Its 
transmission from animal to animal in the 
same stable is usually by bedding and „ _ ^, . 

, -1 • ,1 1 1 r 1 Fig- 6/. — Onorioptes communis 

groommg utensils m the hands of careless ^ar. equi, female; ventral view. 

attendants. 

Scabies op the Sheep 

Sheep may be affected with the following forms of scabies, the first 
mentioned bemg by far the most important in this animal: 

1. Psoroptic scabies, due to Psoroptes communis, var. ovis. 

2. Sarcoptic mange, due to Sarcoptes scabiei, var. ovis. 

3. Chorioptic scabies, due to Chorioptes commimis, var. ovis. 

4. Follicular mange due to Demodex folliculorum, var. ovis. 
Psoroptic Scabies of Sheep. — Through its extensive prevalence 




no PARASITES OF THE DOMESTIC ANIMALS 

among sheep, psoroptic scal)ies may be regarded, from an economic 
stantlpoint, as the most important of all scabies affecting live stock. 
That the disease has been known for many centuries is evident through 
references to it in early writings, including the Bible. The relationship 
of the mite to the disease, however, was not determined with certainty 
until the nineteenth centuiy, during the first half of which the complete 
life cycle of the parasite was demonstrated. It was shown that mites, 
like larger animals, are the offspring of ancestors and are not of sponta- 
neous origin or accidental occurrence. It was further proven by animal 
e.xperinientation that the mites were not present as a result of the scab, 
as had been supposed by some, but that the scab resulted from the 
presence of the mites and could be produced in no other way. 

The psoropt of sheep scab (Figs. 68 and 69) lives upon the surface of 
the body where it is most thickly covered with wool, as the back, sides, 
and shoulders. From their seat of invasion the colonies will spread and 
these areas may coalesce, involving large patches, though the regions of 
shoi't wool, as the belly and front of the chest, are rarely attacked. 

Symptoms and Lesions. — The first indications of the disease are 
iiibbing and gnawmg at the wool and general unrest caused by the itch- 
ing. As the changes m the skin progress loosened tufts become raised 
over the surface of the fleece. These tags are soon rubbed or pulled 
away by the sheep, and the fleece over the affected parts becomes ragged 
and matted, the skin finally becoming more or less bare and showing 
at this stage a thickened, fuirowed, and bleeding condition. 

If the skin is examined before the shedding of the wool there will be 
seen small yellowish nodules and papular elevations of the epidermis. 
The latter with their serous exudate dry up, forming an accumulation 
(jf fatty yellowish scales u]ion the skin and among the deeper parts of 
t he hairs. The papules are closer together as the punctures of the psoropt 
become more numerous. As they become confluent the skin thickens, 
and the drying exudate and papular debris form a massive yellowi-sh 
crust. This, as it increases layer by layer, envelopes and mats the 
wool, lifting the fibers from their follicles and raising large bunches 
above the .surface of the fleece. These detached patches will soon fall 
away, the deimded skin showing a variation of lesions common to 
scabies. It will be thickened, cracked, and scabby, and there may be 
hei'e and there excoriations, with perhaps sloughing and ulcerated areas. 
The acari forsake the more central and older lesions for the periphery 
of the denuded patch where they may be foimd in large numbers at 
the roots of the incrusted wool which in its turn will fall away. Due to 
direct expo.sure to the atmosphere, old denuded or .sheared areas diy 
out and become uniformly covered with a diy parchment-like crust 
beneath which the skin is thickened and fissured. 

Course and Prognosis. — The course and termination of the disease 



THE MITES 



111 



will be influenced by age, condition, character of fleece, and the con- 
ditions under which the sheep are kept. Animals debilitated from age, 




Fig. 68. — Psoroptes communis var. ovis, female: dorsal (left) and ventral 
(right) surface. 

or other cause, offer little resistance, while lambs, due to the tenderness 
of their skin and their dense fleece, are apt to be attacked more severely. 
Sheep with a close wool, as the pure or grade merino, afford an ideal 
habitation for the rapid multiplication of the parasites. The contagion 




Fig. 69. — Psoroptes communis var. ovis, male; dorsal (left) and 
ventral (right) surface. 

of any form of acariases in sheep is facilitated by their hal:>it of living 
in flocks. The disease is, therefore, much more serious in winter when 
the animals are huddled together, especially making rapid progress if 



112 PARASITES OF THE DOMESTIC ANIMALS 

the quarters in which the.v are collected are damp and hot. In summer, 
after shearing and turning upon pasture, it rapidly subsides, in some 
cases even seeming to disappear. 

Psoroptic scabies in sheep, if unchecked, will have a fatal termination. 
Death is preceded by denudation of the greater part of the body, emacia- 
tion, anifiraia, and a progressive weakness. The course is often rapid 
in stabled sheep and those predisposed; within one or two months it 
may have spread over the greater part of the body, while, on the other 
hand, the disease maj' last in a more or less severe form for a year or 
more. 

Transmission. — Sheep scab cannot be transmitted to other animals, 
nor can psoroptic scabies of other animals be transmitted to sheep. 

Sarcoptic Mange of Sheep. — Sheep are rarely affected with this 
form. When it occurs it can at once be distinguished from psoroptic 
scab by its location, which is exclusively upon parts of the body covered 
with short hair. It usually has its beginning about the upper lip or 
nostrils, extending from here to other parts of the face and to the eye- 
lids and ears. In cases of long standing it may spread to the belly and 
inner sides of the front and hind legs. 

Prognosis. — The course of the disease with its typical skin altera- 
tions has alreadj' been described under Sarcoptic Mange of the horse. 
It is much less serious in sheep than in the horse; however, and if taken 
before it has spread extensively, yields easily to treatment. 

Transmission. — Sheep and goats transmit sarcoptic mange recipro- 
cally. It has ))een reported as having been conveyed from these animals 
to man, but such cases, if ever occurring authentically, should be ex- 
tremely rare. 

Chorioptic Scabies of Sheep. — As in the horse, chorioptic scabies of 
the sheep Ijcgins in the hind fetlocks and pasterns where it is charac- 
terized by a redness of the skin and the presence of fine epidermic scales. 
There is considerable itching, causing the animals to stamp their feet 
and bite at the infected parts. Later yellowish crusts appear which 
thicken, and the skin becomes cracked and bleeding, especially about 
the folds of the pastern. Only rarely does the affection pass to the fore 
legs or upward to the udder in the ewe, or to the scrotum in the ram. 

Prognosis and Transmission. — Again, as in the horse, the Chorioptes 
are not inclined to migrate, and the scabies they- produce is but slightly 
contagious. It j'ields promptly to cleanliness and proper treatment, 
subsiding almost entirely' when the flock is turned upon grass in the 
spring. 

Follicular Mange of Sheep. — The follicular mite occasionally in- 
vades the ej'elids of sheep. Few such cases have been recorded, however, 
and, in this country at least, follicular mange is of little importance to 
flock owners. 



THE MITES 113 

Scabies of the Goat 

Goats may be affected by three forms of scabies, — sarcoptic, psoroptic, 
and-chorioptic. The first mentioned is the most frequentlj^ met with in 
these animals, having its seat, as in sheep, mainlj^ about tlie face. The 
other forms are rarely met with in goats. Psoroptic scabies attacks the 
external ear, forming dark-colored, fungus-hke scabs. Chorioptic scabies 
is said to have its beginning on the sides of the neck and withers and 
along the back. 

Scabies of Cattle 

Three forms of scabies affect cattle. These are as follows: 

1. Psoroptic scabies, due to Psoi-optes connnunis, var. hovis. 

2. Chorioptic scabies, due to Chorioptes communis, var. hovis. 

3. Sarcoptic mange, clue to Sar copies scabiei, var. bonis. 

Scabies is less frequent in cattle than in horses and sheep, in North 
America being most often met with in the range herds of the West and 
Northwest. In this country the psoroptic is probably the most fre- 
quent fonn. 

Psoroptic Scabies of Cattle. — This usually has its beginning upon 
the sides of the neck and shoulders, at the base of the horns, or it may 
be at the root of the tail. From these points it usually advances along 
the back, passing to the sides, and m severe cases eventually involving 
the greater part of the body. In its symptoms, course, and skin altera- 
tions it is in all essential respects analogous to the same fonn of scabies 
in the horse. The pruritus is intense, the animal rubbmg and scratching 
itself in every way possible, often causing bloody excoriations of the 
skin. As the disease advances an extreme cachexia sets in, and the 
anaemic and much weakened animal may die in a most miserable con- 
dition. 

Such cases are most likelj' to occur about the close of the winter 
months, especially in cattle stabled or herded together in wann quarters. 
While upon grass, though the infection may remain, its SJ^nptoms sub- 
side, and in the falling away of the scabs with renewal of the coat, maj^ 
even seem to have entkely disappeared. 

Calves, yearlings, and two-year-olds suffer most, and it is among 
these that there is more likeh' to be a fatal termination. 

Chorioptic Scabies of Cattle. — This form in cattle is commonly 
known as tail mange. It generally appears in tlie depressions at the 
base of the tail where as a rule it remains locahzed. If neglected it may 
spread to the loins, perineum, and inner surface of the thighs, or even 
over a considerable surface of the body, though such cases are rare. It 
is exceptional for mange to appear m the feet of cattle. 

Its course is the usual one of chorioptic scabies. The itching is mod- 



114 PARASITES OF THE DOMESTIC AMAL\LS 

erate, and the skin Ijeconies covered with fine, dry scales, later becoming 
denuded, fissured, and scabby. 

It is but slightly contagious and, except in cases of extreme neglect, 
has little tendency to spread upon the body. Where it seems to progress 
bej'ond the limits usual to the choriopt, it should be determined whether 
or not psoroptic scabies is coexisting with it — a condition which is 
Cjuite possible. If this is suspected, material from several affected 
locations should lie examined for recognition of the infecting species. 

Sarcoptic Mange of Cattle. — Mange of the ox due to Sarcoptes need 
be no more than mentioned here. Probably in every case where it has 
occurred it has been by transmission from animals more likely to har- 
bor this species, as the horse or goat. In bovine animals the disease is 
usually of short duration, showing less tendency to spread and yielding 
more promptly to treatment than in the horse. It affects chiefly the 
skin about the eyes and cheeks and may extend to the sides of the 
neck. 

Mange of the Hog 

Two kinds of mange affect the hog. These are as follows: 

1. Sarcoptic mange, due to Sarcoptes scabiei var. suis. 

2. Follicular mange, due to Demodex foUiculorum var. suis. 
Sarcoptic Mange of the Hog. — Sarcoptic mange is considered to be 

the most common form in these animals. The infecting sarcopt is the 
largest variety' of the species and may be seen with the unaided eye as a 
minute moving speck among the removed cutaneous debris. 

Symptoms. — The presence of the disease is first shown upon the 
skin about the eyes and ears, from which points it spreads to the back 
of the neck, withers, shoulders, and l)ack, later, if unchecked, invading 
the greater surface of the body. The pruritus is extremely severe and is 
especially aggravated in animals subjected to the body heat of crowded 
pens. With the extension of the itching nodules the bristles fall out, 
and the skin becomes wrinkled and covered with brownish or dark 
gray crusts. Within the folds the .skin presents the morbid changes 
usual to sarcojitic mange; it is fi.ssiu'ed and bleeding and there may be 
ulcerations. 

Young pigs and those with a thick curly growth of hair suffer the 
most. The condition retards development and fattening, and severe 
cases may lead to general debility and death. 

Transmission. — Contagion is by contact of the animals with each 
other, e.ssentially facilitated when crowded together in pens or lots. 
Because of the habit these animals have of rubbing their bodies, ob- 
jects upon which infected hogs have scratched are especiallv a soiu'ce of 
transmission. 

This mange of the hog may be transmitted to man and to the dog and 



THE MITES 115 

possibly also to the horse, but the eruption produced in such cases dis- 
appears spontaneously in a few days. 

Follicular Mange of the Hog. — Demodex being more difficult to 
recognize, its presence in the skin of pigs probably occurs more often 
than is generally supposed. The skin alterations which the follicular 
mites bring about in these animals is comparatively slight and, as a rule, 
are not such as to perceptibly interfere with general health or growth. 
The primary seat of invasion is usually the skin about the snout. The 
lesions may extend to the cheeks and even to the neck and chest, though 
such spreading of follicular mange in the pig is not often observed. 

Mange of the Dog 

There are three fomas of canine mange, as follows : 

1. Sarcoptic mange, due to Sarcoptes scabiei var. canis. 

2. Follicular mange, due to Demodex folliculorum var. canis. 

3. Auricular mange, due to Otodedes cynolis. 

Sarcoptic Mange of the Dog. — Sarcoptic is considered the most 
common mange affecting the dog. Though it may first appear upon 
any part of the body, it generally begins about the muzzle, especially 
upon the bridge of the nose or, not infrequently, around the eyes, at the 
base of the ears, or upon the breast. As it spreads the ventral surface, 
axilla, and thighs become involved, the morbid process extending with 
such rapidity that by the end of a month it may cover the greater part 
of the body. 

Symptoms, Course, and Lesions. — In its symptoms, course, and 
alterations sarcoptic mange of the dog is similar to that of the horse. 
It is first manifested upon thin and unpigmented skin by little red points 
which are soon converted into papules. These rapidly increase in num- 
ber and, as they rupture and exude their serous contents, deposit a 
scaly accumulation upon the skm followed by the formation of yellowish 
gray crusts. ,As the disease progresses the denuded skin becomes 
thickened, wrinkled, and excoriated, the cheeks, neck, and breast 
especially exhibiting deep folds. The itching, always mtense, is much 
aggravated by an increase in the body temperature, as may be brought 
about by running or warm quarters. 

Where large areas of the bod}' are involved in the disease, emaciation 
and general de^Dility set in, the animal at times givmg off an offensive, 
mouse-like odor. Finally, if the animal is neglected or treatment is 
unsuccessful, death will ensue by the end of two or three months from 
the beginning of the invasion. 

Transmission. — The facts of contagion pertaining to sarcoptic mange 
of other animals apply to this disease of the dog as well. Young dogs 
and those debilitated are predisposed to infection, though dogs of any 
age or condition will support the sarcopt and readily develop tiie disease. 



116 



PARASITES OF THE DOMESTIC ANIMALS 



Follicular Mange of the Dog. — Demodectic mange, or the so-called 
red mange of dogs, is of frequent and world-wide occurrence. The 
lanciform mites enter the orifice of the hair follicle where they multiply 
and occupy the foUicle and sebaceous gland in large numbers, lying 
closel}' pressed together and ahnost invariabh^ with the mouth parts 
directed toward the bottom of the follicle (Fig. 70). In this location 
they may be found m all stages of development, from eggs to sexually 
mature individuals and ovigerous females. As a result of this con- 
stant incrcase^thei'e is a dilation of the hair follicle and gland, the pres- 
sure and irritation producing degenerative 
changes m the lining epithelium of the 
follicle and hair papilla which causes the 
hair bulb to become loosened from its 
attachment. 

Symptoms and Course. — The degree of 
irritation and extension of the inflamma- 
toiy jjrocess to the surrounding tissue will 
be influenced by the number and activity 
of the mites. There may be no more man- 
ifestation of their presence than a hyper- 
secretion of sebaceous material. Where, on 
the other hand, these causative factors are 
sufficient to produce an acute inflammation 
involving the surroundmg derma, there 
will be a dilation of the contained blood 
vessels with mcreased formation of epi- 
dermic cells. Increased desquamation of 
the surface cells follows, and later there is 
an invasion of pyogenic organisms into the 
inflamed and dilated follicles, resulting in 
the formation of pustules and in some cases large abscesses. 

Though follicular mange, owing to its resistance to treatment and 
general septic intoxication, frequentlj' terminates in death, its course 
at the commencement is very slow. In its early manifestations there are 
merely somewhat reddened areas, usuall}- of the skin about the eyes, 
breast, elbows, or it may be at the toes. As the hairs fall awaj- small 
papules are observed, and the affected patches become covered with 
fine, powder-hke scales. The infection is extended by the mites aban- 
doning the origuially invaded follicles and entering the surroimding 
healthy ones, the spreading being aided somewhat by the rubbing and 
licking of the animal. As new parts are invaded the skin becomes de- 
cidedly red and, especially about the cheeks and breast, thickened^ 
wrinkled, and crusty; the eyelids are swollen and covered at their borders 
by a pm'ulent discharge. 




m 



Flo. 70. — Demodex folliculo- 
rum: a, mite greatly eiJargcd; b, 
mites in hair follicle and seba- 
ceous gland — enlarged (after Os- 
born, from Murry, Bui. No. 5, 
Bureau of Entomology, U. S. 
Dept. of .\gr.). 



THE MITES 117 

The disease finally becomes generalized, the skin eveiywhere ex- 
hibiting the lesions in their various stages, and, with it all, exhaling a 
disgusting odor. The pruritus increases, though it remains somewhat 
intermittent, and at no time is as severe as in sarcoptic mange. With 
the generalization of the malady its effect upon the whole animal or- 
ganism is well estabhshed. The appetite is lost and emaciation ad- 
vances, the subsequent marasmus leading to a fatal termination. 

Transmission. — Due to the intra-cutaneous location of the parasites, 
follicular mange is not as contagious as other forms; furthermore a pre- 
disposition is necessary for its development, and this is fomid in 3^oung 
'' and short-haired animals. Adult dogs with healthj'- skins are rarely 
attacked. 

Whether the dermatitis in follicular mange is primarily due to the 
presence of the Demodex may be questioned. The assumption that this 
mite is present in the hair follicles of all dogs needs the support of 
further investigation. Accepting it from clinical observation as a proba- 
bility — and with the predisposing factors of other forms of acariasis in 
mind — there seems good reason to suppose that the mites, living, we 
may say, as commensals, find in erythematous and eczematous skins 
surroundings favoring their nutrition and more rapid multiplication, 
thus bringing about the secondary severe dermatitis of follicular mange, 
the pyodermatitis resulting from subsequent intra-foUicular invasion 
by pyogenic organisms. 

Auricular Mange of the Dog. — Otacariasis is of comparatively fre- 
quent occurrence in dogs, by reason of its contagiousness, being most 
often met with in hounds kept in packs. Symptoms of the presence of 
the mites are frequent scratching and flapping of the ears, which may 
be accompanied by whining and howling. Epileptiform seizures are 
not infrequentl}^ an accompaniment, these especially likely to occur 
when the animal is running. On examination the auditory canal is 
found to contam an adherent, soot-colored powder and a fetid wax 
which may be in sufficient abmidance to produce deafness by obstnic- 
tion of the canal and pressure upon the tympanum. An examination of 
this material imder magnification will reveal the Otodectes in large 
numbers. 

Prognosis. — Otacariasis yields readily to treatment, but if neglected 
may have sei\ious consequences. The animal may die duruig an attack 
of convulsions or, if it survive, be rendered useless as a hunter. 

Mange of the Cat 

The cat may be affected with the two following forms of mange: 

1. Notoedric mange, due to Notoedres cati var. cati. 

2. Auricular mange, due to Otodectes cynotis. 



118 



PARASITES OF THE DOMESTIC ANIMALS 




Fig. 71. — Genus Notoedres. 



Notoedres cati, var. call {Sarcoptes minor var. cati, Fig. 71), the 

dwarf sarcopt, is a small species having the l)ody nearly spherical. The 

dorsal folds of the integument are circular. The anus is dorsal. There 

are six anterior dorsal spinules and but twelve 

posterior. The arrangement of the stalked 

suckers is the same as in Sarcoptes scabiei. 

Course and Diagnosis. — Notoedric mange 
of the cat usually begins al)out the ears and 
upper part of the neck, extending over the 
forehead and then over the head generally. 
As a rule it remains limited to these regions, 
rarely passing to the bodj'. The disease fol- 
lows the usual course and alterations of sar- 
coptic mange, the cat giving evidence of the 
intense itching by frequently shaking the head 
and wiping it with its paws. In neglected 
cases anunals may become nuich emaciated 
and may die in a few months. 

Due to the wrinkled, papular, and crusty 
skin and its persistency of location upon the head, the diagnosis of 
this mange on the cat is not difficult. Its differentiation from other 
itching skin diseases may be made certain by the discovery of the para- 
site, which is readil>' obtained m 
material scraped from lieneath the 
crusts. 

Auricular Mange of the Cat. — 
Auricular mange seldom occurs in 
the cat. It is caused by the same 
species of mite causing auricular 
mange of the dog and is similar in 
its symptoms and course. 

Scabies op the Rabbit 
Two species of scab mites afflict 

therabbit,— A'^0/0«/reSCa<» var. cum- Fk;. 72.— Psoroptes communis var. 

■cult and Psoroptes communis var. cuniculi (from photomicrograph of 
.euniculi (Fig. 72), the latter caus- """"""""^ specimen, by Hoedt). 
ing auricular scabies or psoroptic otacariasis. 

In the rabbit notoedric mange most often has its beginning about the 
nose, from which it extends to the upper part and sides of the head where 
it remains localized. Its location, symptoms, and course are similar to 
those of the same form of mange in the cat. 

Auricular scabies of the rabbit connnences deep in the concha, grad- 
ually involving the skin of the entire inner side. Its presence is first 




THE MITES 119 

indicated by the pruritus which the animal indicates by tossing its head 
and scratching the ears with the hind feet. If the deeper parts of the 
ear are examined early in the disease there will be found a yellowish, 
fetid matter in which many of the mites may be seen with the aid of a 
hand lens. At the end of a few months the greater part of the inner 
side of the ear becomes covered with a thick layer of scabs in which the 
Psoroptes are literally swarming. Usually they remam localized to the 
ear, rarely invading surrounding parts. 

In prolonged cases of auricular scabies rabbits lose their appetites 
and become emaciated, diarrhea sets in, and the animals finally die in 
an advanced state of cachexia. 



CHAPTER XI 
TREATMENT OF MANGE AND SCABIES 

General Considerations. — ^lethods of treatment of scabies will vary 
accorclLiig to the form of the disease to be dealt with and also according 
to the kind and numlter of animals to be treated. As a general rule the 
application of acaricides should be preceded by cliijping the hair from 
either a part or the whole of the body, depending upon whether the 
affection is localized or general. The cnists should then be softened and 
removed bj- washing with warm soapsuds and a stiff brash, after which 
the remedy chosen may be applied. 

The whole process is to be repeated in ten to fourteen days in order to 
destroy mites from eggs which escaped the first treatment. It is im- 
portant that there should be clean surroundings and, especialty where 
emaciation is an accompaniment, an abundance of nutritious food. 
Sarcojitic mange will require more energetic remedies than other 
forms where the mites live upon the surface and among the crusts of 
the skin. 

Internal medication is of little or no value. A cure can only be reached 
by the destruction of the acari, accomplished by the local application of a 
suitable acaricide. In the use of such agents their irritant or possible 
to.xic effects upon the animal treated are to be borne in mind. To avoid 
a sudden and general checking of the cutaneous functions, ointments 
and oleaginous materials are not to be spread over the entire body at 
one application, nor should the body be dressed over more than one- 
fourth to one-half of its area with preparations containing carbolic acid, 
creosote, crcsol, tobacco, or other such ingredients. Those containing 
mercuiy or arsenic, in addition to these limitations, should never be 
used upon animals such as cattle, dogs, and cats as these animals will 
lick the dressed parts. 

Where large numbers of animals are affected in a flock or herd, in- 
dividual treatment involvmg clipping, scrubbing, and the application 
of remedies by hand, is not practicable. In such cases a method of 
dipping must be resorted to. It is essential to the success of the treat- 
ment that thorough disinfection measures be applied to surroundings 
and to such portable paraphernalia as may serve as a means of reinfec- 
tion. In this connection it should be borne in mind that the mites may 
live from two M'eeks to a month or more off a host, the longer periods 
usually amid favorable conditions, such as warm stables and blankets. 



TREATMENT OF MANGE AND SCABIES 121 

The treatments given below deal successively with the different forms 
of the disease and embody such modifications as ma}^ be required for 
the various domestic mammals. 

Treatment of Sarcoptic Maxge 

Treatment of Sarcoptic Mange of the Horse. — Affected animals 
should be isolated in quarters where they will not be in contact with 
each other. Unless the disease is distinctly localized it is better to clip 
the hair from the entire body; its removal will often reveal the lesions 
over areas otherwise unsuspected. The clipping is not to be done in 
the stable or in a wind that will scatter the hairs about. All of the 
hairs should be carefully collected and burned. 

The next procedure is the removal of the crusts in order that the 
remedy used may be apphed directly to the skin. This is best accom- 
plished by the use of soft soap well rubbed upon the scabby surface. A 
thick lather is then formed by the application of a limited quantity of 
warm water. This should be well worked into the crusts with a brush 
and allowed to remain for an hour. The softened crusts may then be 
removed with a brush or, better, a wooden scraper and warm soapy 
water, and the body finally rinsed with clear tepid water applied with a 
sponge. The scraping process should be done gentty and in a manner 
that will add as little irritation as possible to an already inflamed 
skin. After the skin has become perfectly dry it is ready for the remedy 
which is to be applied with a view to the destruction of the parasites. 

There are a number of such remedies in the use of which practitioners 
have had a varied experience. Creosote is among the most effectual. 
It may be used in any of the following combinations: (1) Creosote one 
part, oil sixteen to twenty parts; (2) creosote one part, oil of tar and soft 
soap of each ten parts; (3) creosote five parts, alcohol five parts, water 
twenty parts.. With either of these not more than half of the body 
should be dressed at alternate periods of six days until the entire body 
has had two or three apphcations. It should be applied by rubbing. 

Other remedies which have given satisfactory results are: (1) Lime 
and sulphur dip (Formula No. 1, page 125), two or three applications at 
intervals of one week; (2) creolm and soft soap, of each one part, alcohol 
eight parts. Rub upon one side of the body on alternate days; after the 
body has had three applications rest three days and repeat; (3) decoction 
of tobacco five per cent. Apply over one-fourth to one-third of the body 
each day; repeat three or four times at intervals of one week. 

Unctuous and oilj^ preparations are to be preferred to the more fluid 
ones as they are more penetrating and, adhering to the skin, their action 
is prolonged. For this reason they are especially better suited for the 
treatment of sarcoptic mange. The lime and sulphur preparation is, 



12^2 PARASITES OF THE DOMESTIC ANIMALS 

however, much used and is said to give excellent results. Cure will 
not be complete until all of the mites have been destroyed. Animals 
should therefore be kept under careful observation for some time after 
treatment for the detection of suspicious symptoms, such as itching. 
Such cases may be checked at their incej^tion by less drastic measures 
than at first employed. Often a few applications of mercurial ointment, 
or equal parts of oil and oil of tar containing ten per cent, of carbolic 
acid, rubbed over the limited area, will be sufficient. 

To prevent the reappearance of the disease it is obviousl.y essential 
that harness, clothing, grooming utensils, and all other articles which 
may act as vehicles for reinfection, be disinfected. This is best done 
with Ijoiling water. Articles which might be injured by this treatment 
may be washed with a strong solution (ten per cent.) of lysol or creolin. 

Treatment for mange given at the close of the winter months should 
be repeated in the fall, even though the disease has been apparently 
cured. This is a precautionary measure to destroy the few mites which 
may have survived upon the animal dining the sunnner, and which 
may again produce the disease luider the more favorable conditions for 
their rcprdduction which |)rev;ul dui'ing the fall and winter months. 

Treatment of Sarcoptic Mange of the Hog. — Where but few animals 
are to be treateil they should first be thoroughly cleaned by scrubbing 
with soap and warm water and the skin rinsed and dried. 

The following ointments have been recommended for application 
to the skin aftei' it has been thus prepared: (1) Sublimed sulphur two 
parts, potassium carbonate one part, lard eight parts (Helmerich's 
ponuide); (2) creosote one part, lard twenty-five parts; (3) sulphur ten 
parts, lard thirty parts. These applications are to be repeated three 
times at intervals of about five days. 

Such methods, h<)wever, are out of the question where a large number 
of animals is involved. In such cases dipping in a liquid preparation 
is the only practical form of treatment. For this purpose the following 
lime and suljjhur formula is recommended by the United States Bureau 
of Animal Industry: 

Floweis of sulphur 24 lbs. 

Unslaked hme 10 lbs. 

Water 100 gals. 

Prepare as undei' lime and sulphiu' formulie for scab in sheep (page 
125). 

The hogs should Ije kejjt away from wallows for several days before 
and after dipping. Each animal should be kept in the dip long enough 
for the liquid to be well rubbed into the skin with a stiff brush, care being 
taken that all parts of the body, including the head and ears, are reached 
by the ri^medy. Animals shoukl not be dipped in cold weather. 



TREATMENT OF MANGE AND SCABIES 123 

Essentially, pens and yards must be cleaned up and all litter burned. 

Treatment of Sarcoptic Mange of the Dog. — Dogs should be clipped 
and the skin covered with a thick lather. A good application for this 
purpose is green soap dissolved in an equal quantity of alcohol. Let 
this remain two to four hours, then remove the crusts with a brush and 
warm soapy water. Rinse and allow the skin to become dry. One of 
the following remedies maj^ then be applied: (1) Creosote one part, oil 
fifteen to twenty parts ; (2) creosote one part, green soap and alcohol of 
each eight parts; (3) sublimed sulphur two parts, potassium carbonate 
one part, lard eight parts (Helmerich's pomade); (4) creolin one part, 
alcohol fifteen parts; (5) Peruvian balsam two parts, creolin one part, 
alcohol twenty parts; (6) naphthalin two parts, vaseline eight parts, 
oil of thyme and oil of lavender of each one part. 

The last named mixture is soothing to the skin, agreeable, and quite 
suitable for small house dogs. It is not to be depended upon, however, 
in old and generalized cases. To avoid a too generally irritant or toxic 
effect the acaricide should be applied to not more than one-fourth to 
one-third of the body each dajr. It should be applied freely and energet- 
ically and left on for three or four days. It may then be washed off 
with tepid soapy water. At the end of three or four days the application 
is to be repeated in the same manner, and again repeated until there is 
no further itching or formation of scabs. The animal should be pre- 
vented from licking by fitting it with a broad collar or by binding the 
mouth with tape. 

Preparations of tar had better not be used upon clogs. Remedies con- 
taining carbolic acid, mercury, tobacco, and other poisons are also to be 
avoided, as any measure adopted to prevent licking is liable to be de- 
feated by the dog and a serious poisoning result. 

The usual precautions as to cleaning up of surroundings should of 
course be adopted here. 

Treatment of Notoedric Mange of the Cat. — Cats rebel against and 
actually suffer from washing, therefore treatment of these animals is 
limited to the use of ointments. The hair should be clipped from the 
affected parts and a small amount of vaseline applied which may be 
removed in an hour or two by rubbing with dr.y bran and a cloth, re- 
moving in this operation as many of the crusts as possible. 

The acaricide ointment best adapted to the cat is that of Helmerich, 
consisting of sublimed sulphur two parts, potassium carbonate one part, 
lard eight parts. The application of this is to be repeated at intervals 
of four to six days until scab formation and itching have ceased. It 
may be removed by rubbing in the manner already stated. Peruvian 
balsam is perhaps more effective, but in cats may cause severe cerebral 
disturbance followed by stupor and even death. If used at all it should 
be with extreme caution. 



124 PARASITES OF THE DOMESTIC ANIIVIALS 

Due to the usual location of notoedric mange of the cat upon the 
head, the dressing is inaccessible to lickmg, though the pads of the feet 
are likely to be applied to it and afterward licked. It is scarcely neces- 
sarj' to saj- that preparations contauiing tobacco, cai-bolic acid, and 
other poisons should be strictly avoided in the treatment of cats. 

Treatment of Notoedric Mange of the Rabbit. — Remove the hair 
from the affected area and for a considerable margm around it, apply a 
lather of soft or green soap, allow to remain an hour or two, wash off, 
and repeat as necessaiy to remove scabs. When the parts have be- 
come dry, treat with the ointment of Helmerich as for mange of 
the cat. 

Treatment of Sarcoptic Mange of the Goat. — Clip the hair and 
prepare the parts with soajjy lather as directed for other annuals. Treat 
with a sulphur ointment or a preparation of creosote, as creosote one 
part, oil fifteen parts. Repeat as previously directed. 

Owing to the intractability of goats, dipping is attended with difficul- 
ties and, furthermore, is badly borne by these animals. 

Treatment of Sarcoptic Mange of Sheep. — Remove crusts after 
softening with a lather of soft or green soap, drj', and apply (1) creosote 
one part, oil of tar and soft soap of each twenty parts; (2) sublimed sul- 
phur one part, lard four ])arts, or (3) the ointment of Helmerich may be 
used. Repeat as directed for other animals. 

Treatment of Sarcoptic Mange of Cattle. — After clipping and prep- 
paration of the skiji by removal of the crusts as has been repeatedly 
stated, apply the lime and sulphur mixture as given and prepared luider 
scab of sheep, repeating three or four times at intervals of five days. 
Good results maj- also be obtained bj- the use of sulphur in the form of 
an ouitment, as one part of sulphur to four parts of hog's lard. Prepara- 
tions containing such agents as creosote, l^vsol, or creolm are best limited 
to cases confined to the head and upper parts of the neck, regions in- 
accessible to the tongue. They may be used m the following combina- 
tions: (1) Creosote one part, oil fifteen parts; (2) creosote one part, 
oil of tar and soft soap of each fifteen to twenty parts; (.3) creolin and 
soft soap of each one part, alcohol eight parts; (4) lysol m five per cent, 
solution. 

All of these are to be washed off with soapy water after three days 
and the treatment repeated as necessaiy. 

Treatment of Psoroptic Scabies 

Treatment of Psoroptic Scabies of the Sheep. — Proper hygienic 
conditions and an aljimdance of substantial nourishment will do much 
to protect sheep fi'om the contagion of scab, but where it has made its 
appearance m a flock such measures are only to be relied upon as con- 



TREATMENT OF MANGE AND SCABIES 125 

tributing to a rational treatment designed to rid the sheep of the disease 
by kilHng the parasites. The application by hand of either ointments, 
fluid preparations, or powders for this purpose is practically useless. 
The acaricide chosen for the treatment of psoroptic scabies of sheep 
should be applied by dipping. It is better not to consume time, energj^, 
and patience upon remedies which are not or cannot be used by this 
method. 

Lime and Sulphur Dip. — Many formulae for dips have been pub- 
lished, most of them containing lime, sulphur, tobacco, or arsenic as 
their base. The term " lime-and-sulphur dip" does not refer to an 
exact formula but includes a large number of formulae containing the 
lime and sulphur in different proportions. While the ingrediants of a 
dip should be in such proportion as to make it a reliable parasiticide, it 
is essential that it should cause little or no harm to the sheep or fleece. 
The subject of dips has been carefully gone into by the United States 
Bureau of Animal Industiy and the conclusion reached that probably 
the most effective dips are those containing sulphur and tobacco, and 
sulphur and lime of such strength that they are not injurious to the sheep 
and of minimum damage to the fleece. Among the formulae for lime and 
sulphur dips mentioned by the Bureau are the following (Farmer's 
Bull. No. 159): 

No. 1 

Flowers of sulphur . 24 lbs. 

Unslaked lime 8 lbs. 

Water 100 gals. 

No. 2 

Flowers of sulphur 33 lbs. 

Unslaked lime 11 lbs. 

Water 100 gals. 

For fresh scab, formula No. 1 will act as well as those with a greater 
amount of lime. In old cases with parchment-like scab a stronger dip, 
as fonnula No. 2, is to be preferred. 

The following method of preparing the mixture is recommended bj^ 
the Bureau: 

"A. Take eight to eleven pounds of unslaked lime, place it in a mortor 
box, kettle, or pail of some kind, and add enough water to slake the lime 
and form a 'lime paste' or 'lime putty.' 

"Many persons prefer to slake the lime to a powder, which is to be 
sifted and mixed with sifted sulphur. One pint of water will slake three 
pounds of lune, if the slaking is performed slowly and carefully. As a 
rule, however, it is necessary to use more water. This method takes 
more time and requires more work than the one given above, and does 



1-26 PARASITES OF THE DOMESTIC ANIMALS 

not give any better results. If the boiled solution is allowed to settle, the 
ooze will be equally as safe. 

"B. Sift into the lime paste three times as many pounds of Flowers 
of sulphur as used of lime, and stir the mixture well. 

"Be sure to weigh both the lime and sulphur. Do not trust to measui- 
ing them in a bucket or guessing at the weight. 

"C. Place the .sulphur-lime paste in a kettle or boiler with about 
twentj'-five to thirty gallons of boiling water, and boil the mixture for 
two hours at least, stirring the liquid and sediment. The boiling should 
be continued imtil the sulphur disappears, or almost disappears, from 
the surface, the solution is then of a chocolate or liver color. The longer 
the solution boils the more the sulphur is dissolved, and the less caustic 
the ooze becomes. Most writers advise boiling from thirty to forty 
minutes, but the Bureau obtains a much better ooze bj^ boiling from 
two to three hours, adding water when necessary. 

"D. Pour the mixture and .sediment into a tub or barrel placed 
near the dipping vat and provided with a bung hole about four inches 
from the bottom, and allow ample time (two to three hours, or more if 
necessaiy) to settle. 

"The use of .some sort of a settling tank provided with a bung hole 
is an ab.solute necessity, miless the boiler is so arranged that it may be 
used both for boiling and settling. An ordinary kerosene oil barrel 
will answ<>r very well as a small settling tank. To insert a spigot about 
three to four inches from the bottom is an easy matter. Draining off 
the li(|uid through a spigot has the great advantage over dipping it out, 
in that less connnotion occurs in the liquid, which therefore remains 
freer from sediment. 

" E. When fully settled, draw off the clear licjuid into the dipping- 
vat and add enough water to make 100 gallons. The sediment in the 
barrel may then be mixed with water and used as a disinfectant, but 
tinder no circumstances should it be used fur dipping purposes." 

There are a number of good proprietary dips upon the market which 
will be found convenient anfl effectual. No dip should be used, however, 
unless the ingredients and their exact proportion are known to the user. 
Secret furnnda? put out by irresponsible parties should be avoided. 

Dipping Vats. — Where but few sheep are to be treated the dipping 
anangements may lie quite simple. A tub or trough to which a draining 
lilatform is attached will serve the purpose. A small vat, suitable for 
dipping small flocks, may be constructed of wood or concrete. It should 
be about nine inches wide at the bottom, four feet deep, and two feet 
six inches wide at the top. Its length will depend upon the number of 
sheep to be treated. A convenient length is nine feet at the top, the 
fiooi' having a length of four feet. From one foot above one end of the 
floor an incline with cross cleats rises to the top end of the vat. From 



TREATMENT OF iLA.NGE AND SCABIES 127 

here the incline may lead to a dripping platform which may easily be 
improvised for the purpose. This should be so constructed and applied 
that the drip will flow back into the vat. 

Plans for more elaborate dipping plants, suitable for large flocks, may 
be obtained from bulletins issued by the Bureau of Animal Industiy, 
United States Department of Agriculture. 

To obtain the best results sheep should be sheared before dipping, 
and the dip used at a temperature of 100° to 110° F. Keep each sheep 
submerged two minutes bj^ the watch, forcing the head imder at least 
once just before the animal comes out. The dips should be freshly 




Fig. 73. — A small portable dipping vat for small flocks (from Bull. No. 21, 
Bureau of An. Ind., Dept. of Agr.). 

prepared for each dipping; if permitted to stand for repeated treatment 
failures and i^ossibly injurious effects may result. 

Other Dips. — Tobacco dips, used either with or without sulphur, 
are now mucli in use and give excellent results. Owing to the poisonous 
character of nicotine, the active principle of tobacco upon which these 
dips depend for their action, the exact nicotine content of the dip should 
be known before it is used. This, according to the Bureau of Animal 
Industr.v, should not exceed 0.07 of one per cent. Owing to the variation 
of the percentage of nicotine in different kinds of tobacco and the added 
reason that tobacco dips are somewhat tedious and disagreeable to 
make, it is better to use a reliable tobacco extract, which may be ob- 
tained upon the market, and exactly follow the instructions given for 
the making of the dip. 

Tobacco dip is not injurious to the wool, therefore it has an advantage 
for use upon sheep which may require treatment at a time when they 



1^28 PARASITES OF THE DOMESTIC ANBL^LS 

cannot he safely or profitably sheared. Its disadvantages are that it 
sometimes causes a setback iu the sheep Ij.v sickening them, and that it 
also occasionally sickens persons who work with it, especially if they are 
not tobacco users. 

Dips containuig carbolic acid are easily made and rapid in their action, 
but soon evaporate from the bod}', leavijig the sheep unprotected from 
reinfection. Furthermore, in the strength at which it must be used as a 
reliable acaricide, it causes the sheep to receive a greater setback than 
they do with either the tobacco or lime and sulphur preparation. 

After Treatment. — The dipping is to be repeated upon the entire 
flock in twelve to fourteen days. Where it is necessary to place the 
sheep in the same pasture which they occupied before bemg dipped, 
sulphur should alwaj's be an ingredient of the dip. This remains upon 
the skin and wool and protects from reinfection during the period that 
the acari ma.y remain infective. In anj^ case it is better to place the 
flock after the second dipi:)ing in a pasture which they have not been 
uj)(>n for at least five weeks jirevious to their treatment. 

Treatment of Psoroptic Scabies of Cattle. — As psoroptic scabies of 
the o.\ may become generalized or remain localized upon parts of the 
body easily reached by the tongue, mercurial iirejiarations or those 
containing other poisons which may be licked off should not be em- 
ployed. AVhere one or two animals are affected upon limited areas of 
the body, ointments of sulphur, such as flowers of sulphur one part, 
lard four parts, may be used with good results. The remedy should 
be preceded 1)>' the usual preparation of the skin. After three days it 
can l)e washed off with soaj) and tepid water and the application re- 
peated. 

As a convenient, safe, and effective remedy probably the lime and 
suljihur dip will give better satisfaction than anj^ other for the treat- 
ment of this form of scab in the ox. It should be prepared with the 
jiroportion between lime and sulphur somewhat reduced, as by the 
following fornuila: 

Flowers of sulphur 24 lbs. 

Unslaked lime 12 lbs. 

Water 100 gals. 

Mix according to directions given under lime and sulphvu- formute 
foi' scab in .sheep (page 125). 

Where a small numlier of animals are to be treated the dip may be 
appUed as a spray or with a brush, working it at the same time well 
into the scabs. In larger herds this method is not practical, and the 
animals nuist be treated by dipping. Even though few in the herd 
give evidence of the disease, it is safer to dip all, as it is probable that a 
niunber of the apparentlv healthy have become infected. 



TREATMENT OF MANGE AND SCABIES 129 

Plants for dipping cattle range from the simple to the elaborate after 
various plans. Directions and estimates for the construction of such 
plants, together with much other valuable detail as to dipping, may be 
obtained from the Bureau of Animal Industrj^, United States Depart- 
ment of Agriculture, upon application for bulletins relating to the sub- 
ject (Bull. No. 152). 

The temperature of the dip when used should be from 102° to 108° F. 
Each animal should be kept in it two minutes and be completely sub- 
merged before coming out. The treatment is to be repeated m twelve 
to fourteen days. 

After dipping the precautions against reinfection, alreadj^ referred to 
in connection with sheep scab, are to be observed. 

Treatment of Psoroptic Scabies of the Horse. — The treatment of 
this scabies of the horse does not differ materially from that given for 
mange in the same animal. From the fact that the mites do not burrow 
and thus obtain a degree of protection from the acaricide, it is easier to 
control than the latter form. 

The prehminary application of soap and water, as directed in the 
treatment of mange, should be followed here, after which the same 
general acaricide treatment may be employed. The hme and sulphur 
preparation is probably of more use for this form of scab in the horse 
than for the sarcoptic. It is prepared according to the formulae given 
for scab in sheep (page 125), either formula No. 1 or formula No. 2 being 
used, according to the age and extent of the lesions. It can be applied 
as a spray or with a brush, being at the same time well worked into 
the scabs. The treatment should be repeated at intervals of eight to 
ten days until all indications of the presence of the mites have disap- 
peared. 

The precautions against reinfection, involving disinfection of harness, 
clothing, stalls, etc., as giveir mider equine mange, are to be observed. 

Treatment of Chohioptic Scabies 

Treatment of Chorioptic Scabies of the Horse. — Clip the hair from 
over the affected parts, usually from the hocks down. It is well in an.y 
case to treat the fore legs in the same manner as these may have been 
infected. A portion of the scales and crusts may be removed with a 
brush, after which the parts are to be rubbed with a lather of soft or 
green soap. Let this remain for an hour, then rinse with tepid water, 
sci'ape, and allow to drj-. 

The acaricides mentioned for the treatment of other forms of scabies 
ui the horse will apply here as well. The fact that the affected area in 
chorioptic scabies is usually limited to the lower parts of the legs per- 
mits of the use of remedies which would not be safe for application o^'er 



130 PARASITES OF THE DOMESTIC ANIjVL\LS 

larger surfaces of the body. Strong tobacco decoctions, benzene, or oil 
of turpentine may be used, the latter shaken up in an equal quantity 
of linseed oil. Equal parts of kerosene and linseed oil also give good 
i-esults. Two or three applications of the remedy appHed several days 
apart usually suffices to bring about a complete cure. 

The usual precautions against reinfection should V)e observed. The 
bedding is to be burned and utensils disinfected. Animals should have 
their legs regularly and carefully groomed, and attendants should 
be on the lookout for s\nnptonis of a return of the affection. 

Treatment of Chorioptic Scabies of Cattle. — The curative procedure 
for this scabies does not materiall>- differ from that for bovine mange. 
As chorioptic scabies appears upon parts which may be reached by 
the tongue, preparations containing active poisons should be avoided. 
Probably an ointment of sulphur, as sulphur one part, lard four parts, 
or sulphur two parts, potassium carbonate one part, lard eight i^arts, 
is most suitable for such cases. 

Treatment of Follicular Mange 

Treatment of Follicular Mange of the Dog. — Owing to the intra- 
cutaneous location of the parasites, successful treatment of this mange 
is made very difficult. The jirospects for eventual success will depend 
much ui)on patience and perseverance. It is important that the general 
condition of the animal be built up as much as possible by nutritious 
food and thoroughly sanitary surrounduigs. Such treatment as may 
be adojjteil must be prolonged and often repeated if carried out to 
effectiveness. The remeilies given below for the destruction of the 
mites are among those which have been tried. The best that can be 
said for them is that they have sometimes given good results. 

(1) Peruvian balsam 2 parts, creolin 1 part, alcohol 20 parts. An 
objection to this remedy is its exjDense in view of the prolonged treat- 
ment required. (2) Creosote 1 part, olive oil 15 to 20 parts; (3) benzine 
1 part, olive oil 4 parts; (4) creolin 1 part, green soap and alcohol of 
each 3 parts; (5) repeated applications over limited areas of tincture of 
iodine. (6) In the clinic for small animals at the School of Veterinary 
Medicine, University of Pennsylvania, some encouraging results have 
been obtained from the use of ichthyol, prepared with lard or lanolin 
in the proportion of one to seven. 

Fleming advises that the topical treatment be accompanied by the 
internal administration of sulphur in frequent and large doses; the sul- 
phur being excreted to some extent by the skin. 

Treatment of Follicular Mange of Swine. — Treatment of this form 
of mange in the pig is larely called for. If there are perceptible indica- 
tions of its presence a treatment as recommended for dogs may be tried, 



TREATMENT OF MANGE AND SCABIES 131 

though, due to the intractabihty and habits of pigs, there is probably 
even less prospect of a complete destruction of the mites. The presence 
of Demodex, however, is rarely recognized in pigs, and the effects it 
ma3^ produce are far less serious than in dogs. 

Treatment of Otacariasis of the Dog, Cat, and Rabbit 

Clean the ears of dogs and cats thoroughly and deeply with olive oil. 
It may be applied with a bit of cotton rolled upon a probe which should 
be rotated as it enters the deeper parts. Nocard's treatment, as stated 
by Neumann, is as follows: Naphthol 1 part, ether 3 parts, olive oil 
10 parts. Inject into the external auditory canal each day. After in- 
jectmg close the canal for ten to fifteen minutes with a pledget of cotton. 
This is to prevent the evaporation of the ether. The ether causes the 
remedy to penetrate the waxy lining of the canal which contains the 
parasites. 

In the treatment of rabbits the scabs are first to be softened by a 
thick lather of soft or green soap which should be allowed to remain for 
an hour, rinsed, and repeated as may be necessaiy for deep crust forma- 
tion. The deeper parts of the ear may then be cleaned with olive oil 
and cotton as directed for dogs and cats. 

As an acaricide, the same treatment may be employed as recommended 
for otacariasis in dogs and cats, applying the remedy with a pledget 
of cotton over the whole inner surface of the concha as well as injecting 
it into the auditory canal. An ointment of sulphur, or a liniment com- 
posed of benzene and olive oil equal parts may also be used, either to 
be applied with a pledget of cotton rolled upon the end of a probe or 
stick. 

It is a good precautionary measure to treat the ears of all rabbits 
which have been exposed, as there may be mfections of a latent chai- 
acter which will later bring about another outbreak of the disease. 



CHAPTER XII 

MANGE OF POULTRY 

The acari-produciiig mange of fowls belong with the genus Cnemi- 
doeoptes, the characteristics of which are described on page 103. There 
are two species, — Cn. mutans (formerly' Sarcoptes 7nutans), which pro- 
duces the condition known as scaly leg, and Cn. gallince {Cn. lavis) 
which attacks the skui at the attachment of the feathers. 

Mange of the Legs ("Scaly Leg"). — The burrowing mite of leg 
mange most often attacks the feet and legs of chickens of the heavier 
breeds, as the Brahma, Dorking, and CochLn China, less frequently 
turkeys, pheasants, and pigeons. 

The mites live under the epidermic scales from the tarsal joint down- 
ward, including the upper part of the toes. In this location they deposit 
theii- eggs anti multiply, the irritation of their presence soon being 
manifested by the formation of a white powdery matter which elevates 
the scales. Due to the exuded serum, this matter assumes a lardaceous 
nature, adhering to and soon co\'ering the foot. Gradually rough crusts 
are formed in the lower layers of which numerous mites may be found. 
The scabs adhere closely to the skin, and, when removed, reveal an 
irritated and bleeding surface (Fig. 75). 

The course of the disease is slow, running several months to a year. 
There is a moderate pruritus which the fowl indicates by restlessness 
and picking at the scabs with the beak. As the crusts increase there 
is a mechanical interference with flexion of the jomts which makes 
either moving about or standing difficult. As a consequence the animal 
often squats down with the legs extended and remains in this position 
with infrequent efforts to rise. In such severe cases arthritis is likel.v to 
appear, and one or even all of the toes may drop off. When the disease 
has advanced over several months we have the usual systemic accom- 
paniment of prolonged mange; there is loss of appetite, cachexia, and 
stupor which is usuall\- followed by death. 

Treatment. — Treatment must begin with softening of the scabs with 
soft soap, applied by hand or by soaking in warm soapy water. The>' 
m&y then be removed by manij)ulation with the hands or with a bru.sh, 
care being taken in this operation to cause as little injur}' to the skin as 
possible. When the parts are dr\', appl.v Peruvian balsam, either alone 
or made up in the proportions of balsam 2 parts, creolin 1 part, alcohol 
20 parts. The ointment of Helmorich, as recommended for scabies in 



MANGE OF POULTRY 133 

other animals, is one of the best remedies for this scab. Others perhaps 
as effectual are (1) creosote 1 part, lard 20 parts; (2) benzene 1 part, 
olive oil 10 parts; (3) carbolized vaselme (5%), or (4) an ointment of 
carbolic acid 1 part, lard 20 parts. The stronger acaricides should not 
be used upon yoimg chicks. For these the ointment of Helmerich or 
Balsam of Peru are quite suitable. The application may be washed off 
and repeated as necessary. 

To prevent contagion and reinfection, diseased fowls should be re- 
moved from the healthy and the quarters subjected to cleaning up and 
disinfection, especial attention being given to roo.sts and other places 
where the fowls are in the habit of perching. 




Fig. 74. — Cnemidocoptes mutaus, male and female (after 
Osborn, Bull. No. .5, Bureau of Entomology, U. S. Dept. of Agr.). 

Mange of the Body, or Depluming Mange. — The depluming mite, 
Cnemidocoptes gallince, is closely related to the mite of foot mange and 
it maj^ easily be mistaken for the same species where the two forms of 
mange coexist. The body form usually has its begmning on the back, 
near the insertion of the tail-feathers. More rarely the head and upper 
part of the neck are first attacked. From these regions it spreads to 
adjacent parts of the bodj^ 

The disease is accompanied by the production of an abundance of 
epidermic scales, irritation, and itching which impels the fowl to pluck 
at the feathers. These easily drop out or are broken off, leaving a bald 
or partlj'' denuded skin which is laut little thickened and remains normally 
smooth and elastic. 

The acaricide treatment employed may be the same as for foot mange. 
Where a number of birds are affected they may be treated hy dipping 
for several successive days in a sulphur bath. The same precautions 
against contagion and reinfection are to be observed as for the leg form. 
In this connection it is well to repeatedly dismfect the feet of roosters. 



134 



PARASITES OF THE DOMESTIC ANIMALS 



C3rtoleichus nudus. 



as the disease is readily conveyed from the back of one hen to another 
in treading. 

Family V. Cytoleichid^ 

Acarina (p. 94). — This family contains two genera, Cytoleichus and 
Laminosioptes, each with one species causing a deep-seated acariasis in 
birds. 

Cytoleichidje (p. 134). — The body is rounded, 
almost bald, and whitish in color. The 
mouth parts are conical. The legs have five 
articles and are strong and elongated; all 
terminate by a simple stalked sucker. The 
ovigerous female is 500 to 600 microns long 
l)y 3.50 to 400 microns broad. She may pro- 
duce either larvae or eggs. 

Colonies of these parasites live in the air 
passages and air sacs of fowl. 

Laminosioptes cysticola. Cytoleichidse 
(p. 134). — The body is twice as long as 
broad; color grayish. On the dorsal surface 
are several pairs of liristles, a long pair ex- 
tending from the posterior extremity. The 
mouth parts and the two first pairs of legs 
are carried upon the anterior third of the 
liody which is separated from the posterior 
portion by a transverse furrow. The legs 
are short, smooth, and provided with 
suckers, which are not permanent upon the 
anterior pair. The ovigerous female is 250 
to 2(30 microns long by 100 to 110 microns 
broad. 

Pai'asitic in subcutaneous connective tis- 
sue of fowl. 

The Cytoleichus species enter the respir- 
atory passages and pass to the deeper air 
channels, even to the air canals in the bones. 
From their relatively large size and whitish 
color they may be readily seen with the naked eye, usually in colonies 
of more or less number. Ordinarily these parasites do not cause suf- 
ficient disturbance to betray their presence during the life of their host. 
If in exceptionally large numljers they may cause attacks of coughing 
by irritation of the bronchial mucosa. 

Laminosioptes cysticola lives in the subcutaneous connective tissue, 
especially in regions where this is loose, as the neck, breast, sides, and 




Fig. 75.— Foot of fowl affected 
with scaly leg. 



MANGE OF POULTRY 135 

thigh. Where many are present they cause irritation witli the forma- 
tion of yellowish, oval nodules. These are about 0.5 mm. by 1 mm. 
in dimensions, and a large number of them may cover a small area. They 
are soft, granular or calcareous, and may contain the dead parasites. 
The health of the host does not appear to be affected by the lesions 
which these parasites produce. 



CHAPTER XIII 

THE TICKS 

There has been coiisitlerable difference of opinion among various 
authors as to the sj-steniatic arrangement of the ticks. They have 
been brought into one family, — Ixodidse, in which two subfamilies are 
distinguished, — Argasinse and Ixodinae, and, again, these two subgroups 
have been considered as distinct families. The arrangement adopted 
here, which raises the ticks to the rank of a superfamily, is that of Banks 
(1894) and as followed ]>y Salmon and Stiles (1901). 

Structure of Ticks in General. — The proper study and differentiation 
of the ticks recjuircs some Iviiowlcdge of the external parts and an under- 
standing of the tecluiical terms which are used in reference to them. 
Conforming to the general characteristics of the order Acarina to which 
they belong, the ticks have a body in which the cephalothorax and 
abdomen are not demarcated and this bears certain structures possessing 
variations as to location and form which serve as defining characters 
for the ^-arious suligroups and si:)ecies. The parts more connnonly 
referred to with their technical names follow: 

1. The Capitidum (Fig. 7G) is the "head," "false head," or rostrum, as 
it is variously termed. It j^i-ojects from the anterior extremity in the 
Ixodida?. In the Argasid;r, excejit in the larval stage, it is upon the 
under surface of the anterioi- extremity. The structure consists of a 
number of parts, as follows: 

(a) The Ba.'iis Capituli (Fig. 76, b) is the hard base of the capitulum; 
the ba.sal ring or mouth shield. 

(b) The Hijpofitonie (Fig. 76, h) or "labium" or "radula" of various 
authors is a median ventral structure rising from the basis capituli and 
bearing lecurved teeth. 

(c) The Chelicerw (Fig. 76, c), "mandibles," or "jaws" are paired 
elongate structures, one on each side of the median line, lying dorsal 
to the hypostome. Dorsal to these is the hood or sheath of the chelicerse. 

The hypostome, chchcerjE, and hood constitute the haiistelluin, or, as 
it is commonly called, the "beak," and it is these structures which pen- 
etrate the skin of the animal upon which the tick attaches. 

(d) The Palpi (Fig. 76, p) are articulated structures, one on each 
side of the haustellum, and inserted antero-laterally upon the basis 
capituli. 

2. The Scutum (Fig. 77), or dorsal shield — present in the Ixodidse, 



THE TICKS 



137 




Fig. 76. — Capitulum (rostrum), 
of an argasid tick: h, hypostome; 
c, chelicerse; p, palpi; b, basi-s 
capituli. 



absent in the Argasidfe — is a hard, plate-hke structure located inune- 
diately posterior to the capitulum. In the male it usually covers the 

entire, or almost the entire, dorsal surface, 
in nj-mphs it covers the anterior portion; 
while in the adult female it is much smaller 
and confined to the anterior portion of the 
body. 

3. Dorsum. — This term refers to the 
whole dorsal surface of the bod3^ 

4. Festoons (Fig. 82) are uniform rect- 
angular areas into which the posterior mar- 
gin of the l3ody is divided up. Usually 
eleven may be more or less distinctly rec- 
ognized. They are most distinct in xmfed 
specimens, but almost or entirelj^ disap- 
pear in distended females. Thej^ are not 
present in all forms. 

5. Piindations are circular depressions 
upon the integinnent from which fre- 
quently issue hairs. 

6. Ornamentation refers to enamel-like coloration which may be pres- 
ent on the scutum, capitulum, or other parts. Ticks upon which this 
coloration occurs are re- 
ferred to as ornate. 

7. Venter. — This term 
refers to the whole ventral 
surface of the body. 

8. The Spiracles (Figs. 
78 and 78, a) — also called 
stigmata, stigmal plates, 
and peritremes — are two 
respiratory organs sit- 
uated ventro-laterall}'. In 
the Ixodidse they are sit- 
uated posterior to the 
attachment of the fourth 
pair of legs; in the Ai'g- 
asidae they are between 
the third and fourth pairs. 
The entire structure may 
be considered as the 
stigmal plate or peritreme 
with an opening known as 
the spiracle or stigmal aperture. The stigmal plates vary in form and 




Fig. 77. — Capitulum (head), srutum (shield), and 
foreleg of Margaropus annulatus (from photomicro- 
graph of mounted specimen, by Hoedt). 



138 



PARASITES OF THE DOMESTIC ANIMALS 



structure in different species; they may he circular, oval, or comma- 

shai^ed. 

9. The Genital Pore is a transverse ventru-niedian slit, situated ante- 
riorly between the at- 
tachments of the first 
three pairs of legs. 

10. The Anus is in the 
ventro-median line, pos- 
terior to the attachment 
of the last pair of legs. 

11. The Anal Shields 
are four elongate struc- 
tures lateral to the anus. 

They are present only in males of certain genera. 

12. Legs. — There are four pairs of legs in the adult males and females 
and in the nymphs (octopod). In the larvse there are three pairs (hex- 




FiG. 78. — Stigmal plates of ticks: 1, Margarnpus: 2. 
Ixodes; .3, Derraaccntor. 




Fig. 78.\. — Stigmal plate of Margaropus annulatus (photomicro- 
graph of mounted specimen, by Hoedt). 

apod). The pairs are numbered I to IV from before to behind. They 
are composed of six articles or segments which are united by articul- 
ations. 

13. The Coxa or first article is an innnovable portion which lies flat 
upon the body and upon which the first movalile article is articulated. 



THE TICKS 



139 



14. Bifid Coxce bear two spurs and are deeply incised. When tren- 
chant they have a knife-like margin. 

Several stages are passed through in the development of the ticks. 
From the eggs are hatched thesix-legged (hexapod) larvce, often referred 
to as the "seed ticks" (Plate II, Fig. 6). These are very small but 
may be seen without the aid of magnification. The legs are relatively 
much longer than in the adults. 

The nymph stage is reached after molting, when a fourth pair of legs 
appears posterior to the third pair (octopod). 

The change from the njinphal to the adult stage is marked by another 
molting, and sexual maturity is reached. 

After fertilization b}^ the male, the female slowly enlarges and be- 
comes the ovigerous or egg-containing female. Upon repletion she drops 
to the ground and proceeds to deposit her eggs. 

Superfamily Characteristics. Acarina (p. 94). — The Ixodoidea are 
all blood-sucking parasites on animals. Thej' have a movable capitulunr 
consisting of a basal portion (basis capituli), protrusible serrate chel- 
icerse, a rigid serrate hypostome, and a pair of palps. The breathing 
apertures are situated posteriorly. 

The superfamily Ixodoidea is divided into two families, — Argasidse 
and Ixodidse. 

Family I. Ahgasid^ 

Ixodoidea (p. 139). — The ticks belonging with this family have little 
sexual dimorphism as compared with the Ixodidse. The capitulum, 
instead of being terminal, occupies in adults the ventral face of the 




/■.^3 



Fig. 79. — Argas miniatus: Fig. 3, dorsal view; 3a, ventral view; 3c, larva (after Os- 
born, from Marx, Bui. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 

cephalothorax. The palps are leg-like, the article.? very movable on 
each other. The scutum is absent. The coxa? are unarmed; tarsi with- 
out ventral spurs. 

The family has two genera, — Argas and Otobius. 

1. Argas miniatus (A. americanus) (Fig. 79). The Fowl Tick. Ar- 
gasidie (p. 139). — The l)ody is ovoid, flattened, with edges very thin. 



140 PARASITES OF THE DOMESTIC ANIMALS 

Depending on the stage of engorgment, the color varies from light 
reddish to dark brown. The capituknn has four long hairs, all directed 
forward. The adult females are about 8.5 mm. (5/16 of an inch) in 
length. The males are slightly smaller, but are not easily distinguish- 
able. 

Occurrence and Habits. — Commonly called the "fowl tick" or 
" adol)e tick," this species is widely distributed. It is a parasite of fowl in 
Europe, Asia, Africa, and Australia, m Mexico and the Southern United 
States. In its habits it is comparable to the bedbug, coming out to 
feed upon its host at night and retreating after engorgment to cracks, 
crevices, or other darkened hiding places to remain durmg the day. In 
these retreats the females deposit large, reddish brown eggs, usuallj^ 
several lajangs, iu masses containing up to a hundred or more eggs in 
each. Herms (1915) gives the further life history as follows: "Hatchmg 
takes place in from three to four weeks. The larva are six-legged and 
verj^ active, attacking a host apparent!}^ as readily by day as by night. 
Once attached the larvie feed for about five days, occasionally longer, 
remaining fii-nili,' attached during this time. At the end of this feeding 
period the larvae detach themselves and then crawl away from their 
host, hiding in some convenient crevice near by. The larvae molt in 
about a week, when the fourth pair of legs appears and they are now in 
the first nymjjhal stage, appearing like miniature adults. Nocturnal 
feeding now takes place and in ten or twelve days another molt 
occurs and the second n\nnphal stage is reached. Again the tick at- 
taches itself, being now able to engorge itself in about an hour; again 
after the oxi)iration of something over a week a third molt takes place 
and the adult stage is i-eached. The adults are able to engorge them- 
selves in from twenty to forty-five minutes." 

Effect. — When attacking in large numbers these parasites extract 
large ciuantitios of blood and, furthermore, cause much irritation and 
unrest among (ho flock. As a result the animals become unthrifty, 
weak, and nonjiroductive. 

Argas miniatus has been proven to be the carrier of the spii'ochete 
(Spirodieta galUnarum) causing fowl spirochetosis or Brazilian sep- 
ticemia of fowls Cp. 327). 

Control. — For the eradication of this pest the same general methods 
may be taken as reconunended for bedbugs of the hen house (p. 92). 
The ends of roosts should be repeatedly covered with tar or wrapped in 
waste soaked with criide oil. Nesting and trash should be burned and 
the interior sprayed with kerosene. All woodwork about the buildings 
should Ijc free from bark, as this affords a favorable hiding place for the 
ticks. It is well to repeat the treatment with kerosene at least once a 
month during the season that the ticks are active. 

2. Otobius megnini (Ornithodorus megnini, Fig. 80). The Spinose 



THE TICKS 



141 



Ear Tick, Argasidae (p. 139). — The body is oval, broader anteriorlj' than 
posteriorly. The female is 5-6 mm. (}4, of an inch) in length and about 
3 mm. C/s of an mch) in breadth. The njanphs are covered with nu- 
merous spines, a fact which has given to this species the common name 
"spinose ear tick." 

Occurrence and Habits. — This tick occurs in the ears of horses of 
Mexico and the Southwestern States. Its attack is not confined to 
horses and mules; it also attacks the ears of cattle and occasionally other 
domestic animals and man. The larval ticks reach the head of the graz- 
ing host animal from weeds or other vegetation upon which the_v have 
crawled immediately after 
hatching. Having gained en- 
trance to the ear, they attach 
deeply in the folds where they 
feed for about five days. 
They then molt and, as 
nj-mphs with spinose bodies, 
contmue to infest the ear and 
feed for several weeks. The 
npnphs then leave the host, 
again molt, and becoming 
unspined adults, the females 
are fertilized and soon begin 
depositing their eggs. 

Effect. — In their attach- 
ment to the lining of the 
concha; the spinose ticks 
cause much irritation which 
the animal indicates by shak- 
ing its head, or it maj^ be 
wrought up to a high degree of nervous excitement. The ticks are said 
to be responsible for much deafness among domestic animals, and, 
especially among young animals, they are considered as a cause of se- 
rious illness and even death. 

Treatment. — Good results have been obtained by flooding the ear 
with carbolized oil. This closes the breathing apertures of the ticks and 
causes them to release their attachment, after wliich the}' may be re- 
moved with a cotton swab or forceps and destroyed. 




Fig. 80. — Otoljius megnini: dorsal and ventral 
view of nymphal form, with details (after Osborn, 
from Marx, Bull. No. 5, Bureau of Entomologj", 
U. S. Dept. of Agr.). 



Family II. Ixodid.e 

Ixodoidea (p. 139). — The most prominent differential character by 
which these ticks maj- be distinguished from those of the famih' Ar- 
gasidae is the presence of a scutum, located immediately posterior to 



Ul PARASITES OF THE DOMESTIC ANIMALS 

the capitulimi, which is tenninal and not upon the ventral face of the 
cephalothorax as in the Argasidse. Sexual dimorphism is marked, the 
dorsal surface of the males being- almost covered by the scutum. In 
the tiistended female the scutum appears as a small shield directly lie- 
hind the capitulum. Only the females are capable of great distension. 
The spiracles are posterior to the fourth coxae. The eyes, if present, are 
situated laterally upon the scutum. 

Nine genera have been described imder the family Ixodidae, as fol- 
lows: Ixodes, Hsemaphysalis, Dermacentor, Rhipicentor, Rhipicephalus, 
Margaropus, Boophilus, Hyalomma, and .\mblyomnia. 

Four of the above, — Ixoties, Dermacentor, Margaropus, and Am- 
blyomma, — contain species occurring upon cattle and other animals in 
the United States. The generic characteristics of these are given by 
Nuttall and Warburton (A Monograph of the Ixodoidea, 1911) as 
follows : 

1. Ixodes. — Inornate, without eyes and without festoons; spiracles 
round or oval; palps and basis capituli of variable form; coxae either un- 
armed, trenchant, .spurred, or bifid; tarsi without spurs. Sexual di- 
morphism pronoimced, especially with regard to the capitulum. In 
the male the venter is covered by non-salient plates: one pregontial, 
one median, one ana!, two adanal and two epimeral plates. Anal groove 
surrouniling anus in front. 

2. Dermacentor. — Usually ornate, with eyes and festoons; with 
shoi't, broad or moderate palps and ba.sis capituli rectangular dorsally. 
In stnut' sijecies coxse I to IV of the male increase progressively in size; 
in all species coxa IV is much the largest; the male, moreover, shows no 
ventral jilates or shields. Coxa I bifid in both' sexes. Anal groove con- 
toiu'ing anus behind. Spiracles suboval or comma-shaped. 

3. Margaropus. — Inornate, with eyes, but without festoons, with 
short palps and capitulum intermediate between that of Rhipicephalus 
and Hoiiphilus; highly chitinized; the unfed adults of large size. The 
female with very small scutum. Coxae conical, unarmed but for a small 
spine posteriorly on coxa I. The male with a median plate prolonged 
in two long spines projecting beyond and to either side of the anus; 
with coxie similar to those of the female; legs increasing progressively 
in size from pair I to IV, the articles, especially of leg-pair IV, greatly 
swollen. When replete, the male shows a caudal protrusion. Anal 
groove obsolete. Spiracles rounded or short oval in both sexes. 

4. Amblyomma. — Generally ornate, with eyes and with festoons. . 
With long palps; of which article II is especially long, ba^sis capituli of 
variable form. The male without adanal shields, but small ventral 
plaques are occasionally present close to the festoons. Anal groove 
contouring anus behind. Spiracles subtriangular or comma-shaped. 

Six .species are found upon cattle and other domestic animals in this 



THE TICKS 



143 



country, the following brief descriptions of which are taken principally 
from those given by Mohler (Bull. No. 78, Bureau of Animal Industry, 
190.5; Farmers' Bull. No. 569, 1914). The parts described are those of 
the adult female. 

1. Ixodes ricinus (Fig. 81). The Castor-bean Tick. Ixodes (p. 
142). — The body is ovoid in shape, narrower anteriorly than posteriorly; 
lead colored, with a diversity of yellowish red, brown, or gray. Festoons 
are absent. The mature female is three-eighths to seven-sixteenths of 
an inch in length. The legs are thin and dark brown in color. The 
capitulum and scutum are a shiny dark brown or chestnut brown; 
scutum pentagonal with prominent lat- 
eral borders. The palpi are well de- 
veloped and extend outward upon each 
side. 

This tick has been collected from sheep, 
goats, cattle, horses, deer, dogs, foxes, 
cats, rabbits, birds, and man. It is 
widely distributed in the United States. 

2. Ixodes hexagonus. The European 
Dog Tick. Ixodes (p. 142).— The body 
is oval in shape and of an ashy color; 
festoons absent. The legs are longer and 
more robust than those of the cattle tick. 
The capitulum and scutum are brownish 
red in color and similar to those of 
Ixodes ricinus in shape. The palpi are 
longer and more prominent than in the 
cattle tick and, like those of Ixodes ricinus, extend outward. 

This species has been collected from dogs, cattle, sheep, foxes, rabbits, 
squirrels, gophers, cats, birds, man, and other hosts in the Eastern 
United States, but is less common in this country than the other species 
here described. 

3. Dermacentor reticulatus (D. occidentalis). The Net Tick. 
Dermacentor (p. 142). — The body is oblong oval, five-eighths of an inch 
long, and of a deep brown or slate color. The legs are brown and of 
moderate length. There are eleven festoons about the posterior margin 
of the bod}^ which in the adult become shallow or effaced. The scutum 
has a silvery-white metallic rust extending along the two sides and 
posterior portion. 

Found on man, cattle, horses, sheep, and deer. In this country it 
seems to be most common in the West, especially in California, Texas 
and New Mexico. 

4. Dermacentor variabilis (D. electus, Fig. 82). The American 
Dog Tick or Wood Tick. Dermacentoi' (p. 142). — This tick resembles 




Fig. 81. — Ixodes ricinus — enlarged 
(after Osborn, Bull. No. 5, Bureau 
of Entomology, U. S. Dept. of Agr.). 



14.4 



PARASITES OF THE DOMESTIC ANIMALS 



D. reticidalus so closeh' that a hand lens is necessary to distiiiguish be- 
tween them. The Ijody is oblong oval ui shape and ma,v measure as 
much as three-fifths of an inch m length. It can be distinguished from 
the Texas-fever tick liy the capitulum and scutum which are longer and 
broader. Extendmg anteriorly along each side of the scutum there are 
Imes of yellowish white rust, separated by a central brownish area. 
There are eleven festoons on the posterior margin of the body, most 
distinct in the j'oung female. 

This tick has been found on man, cattle, dogs, horses, and other an- 
imals, es])ecially in the Eastern United States. 




Fig. 82. — Dermacpntor \'ari:ibili.s: male — enlarged (after Os- 
born, Bull. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 

o. Margaropus annulatus (Boophilus annulatus, B. bovis). The 

Texas-fever or Cattle Tick. Maigaropus (p. 142). — This tick may be 
distinguished from the other five by the small size and the color of the 
cai)itnlum and scutum, the lateral borders of which are straighter and 
more parallel. These parts are short and relatively' broad and in color 
reddish brown or chestnut brown. The body is oblong oval in shape 
and may reach a length of one-half an uich. The color maj^ be dull 
yellow or olive brown. Often it is mottled with irregular areas of 
yellow and brown or streaked with wa\'y lines of these colors. Festoons 
are absent. The legs are brown, moderately long, and very slender. 

This tick is found principally on cattle, less frequently on horses, 
mules, and asses. 



THE TICKS 145 

6. Amblyomma americanum. The Lone Star Tick. — Amblyomma 
(p. 142). — The body is oval and in color 3rellowish graj^ or brown. 
When not distended, the body-surface is rough and puckered. Festoons 
are present. The scutum extends backward a short distance to form a 
triangle, at the apex of which is a white or j^ellowish spot, from which 
the tick derives its name "Lone Star." The mature female may reach 
a length of one-half an inch. The legs are long and thin. 

This species has been foiuid on cattle, dogs, horses, sheep, goats, hogs, 
and man. It is very widely distributed in the United States. 

All of these ticks show longitudinal grooves upon the dorsal surface 
of the body which are most distinct a few days after the tick's repletion 
and removal from the host. These furrows vary considerably in different 
members of the same species and, though some authors appear to attach 
importance to them, they can hardly be considered of much value as an 
aid in recognition. Color is also unrehable m the identification of 
genera and species, as this varies with the stages in the tick's develop- 
ment and may change variously in adult ticks of the same species. 

The Texas-fever Tick. — Kilborne, of the Bureau of Animal Industiy, 
proved conclusivel^y bj' field expermients conducted in 1889 and 1890 
that it is only through the bite of this tick that Texas-fever can be 
naturally transmitted. Economically, therefore, Margarojnis annulatus 
(Plates I and II), the Texas-fever tick, is the most important for con- 
sideration. Other ticks not concerned in the transmission of Texas- 
fever have been mentioned here as occurring upon cattle, all having 
the same successive stages in their development, namely, oval, larval, 
nymphal, and adult male and female. Before molting and transforming 
from one stage to the other these ticks fall from their host, after the 
transformation seeking a new host. That this is not true in the case 
of the Texas-fever tick was shown by Dr. Cooper Curtice, of the Bureau 
of Animal Industry, in 1891. He established the fundamental facts 
in the life history of this tick and showed that it remains upon its host 
from the time that it attaches as "a larva until it drops to the ground 
replete and readj^ to deposit its eggs (Tables, p. 151). Careful observa- 
tions by the Zoological Division of the Bureau have supplied valuable 
data relative to the biology of this tick, and much detailed information 
has been published by the Bureau pertaining to this and to tick control 
and eradication. In this connection, it may be of service to mention 
here the following titles, any of which can be obtaiiied upon application 
to the Superintendent of Documents, Government Printing Office, 
Washington, D. C. 

Texas Fever, Methods for its Prevention, liv John R. Mohler. Bull. 
No. 78 (1905). 

Texas or Tick Fever and its Prevention, bv John R. Mohler. Farmers' 
Bull. No. 258 (190G). 




Plate I.— Margaroijus annulatus: 1, Male, dorsal view; 2, Female, dorsal view 3 
Male, ventral view; 4, Female, ventral view; .5, Claw and pulvillus; 6, Lower surface of 
hrst second, and third segment of leg; 7, .Stigmal plate. (After Osborn, from Curtice, 
iiull. No. o. Bureau of Entomology, U. S. Dept. of Agr.). 




Plate II. — Margaropus annulatus: 1, Front foot, showing single spur; la, Supposed 
sense organs; 2, Hind foot, showing double spur; 3, Head of female; 4, 4a, 4b, 4c, Female 
ticks, natural size, shown at different stages of feeding; 5, Egg; 6, Larval or "seed" tick; 
7, Dorsal surface of the mouth parts of female — a, mandible; b, labrum; c, palpus; d, 
mouth ring; e, spots covered with papillae; 8, Labium and mandibles; 8a, Papilla enlarged; 
9, Mandible-X-Busk's organ, use unknown ; 10, Mouth parts of young tick. (After Osborn, 
from Curtice; Bull. No. 5, Bureau of Entomology, U. S. Dept. of Agr.). 



148 PARASITES OF THE DOMESTIC ANIMALS 

The Cattle Tick in its Relation to Southern Agriculture, bj' August 
Mayer. Farmers' Bull. No. 261 (1906). 

Proceedings of a Conference of Federal and State Representatives 
to Consider Plans for the Eradication of the Cattle Tick. Bull. No. 97 
(1907). 

Methods of Eradicating Cattle Ticks, by Louis A. Klein. Cir. No. 
110 (1907). 

Studies on the Biolog>' of the Te.xas-fever Tick, bv H. W. Gravbill. 
Bull. No. 130 (1911). 

Methods of Exterminating the Texas-fever Tick, bv H. W. Gravbill. 
Farmers' Bull. No. 498 (1912). 

Progress and Prospects of Tick Eradication, bj' Cooper Curtice. 
Cir. No. 187 (1912). 

Texas or Tick Fever, by John R. Mohler. Farmers' Bull. No. 569 
(1914). 

Life History; the Nonparasitic Development. — The following data 
as to the life histon' of the Texas-fever tick is taken from Graybill 
(Studies on the Biology of the Texas-fever Tick, 1911). The non- 
parasitic develojiment is considered l\y this author under five periods, 
nameh', the preoviposition period, the oviposition period, the incu- 
bation period, the hatching period, and the longevity period of the 
larvaj. 

The iieriod of preoviposition extends from the time the female tick 
drops luitil she begins to deposit her eggs. In a series of investigations 
carried out at Aulnu-n, Ala., in 1907-8 it was observed that the average 
duration of this period ranged from three to forty-nine and three-tenths 
daj-s, depending lai-gely upon temperatiu'e, the shorter average period 
occurring in August, the longer in December. 

The average o^•iposition or egg-Iaymg period for different months of 
the year ranged from eight and three-tenths da.ys for June to one hun- 
dred and twentj'-seven and five-tenths days for November. The 
maxinnnn period noted was one hundred and fifty-two days, observed 
in November, and the muiinrnm three days, observed in June. The 
maximiun number of eggs deposited by a female tick was 5105, minimum 
357, with an average ranging from 1811 to 4089. 

The incubation period was found to range from nineteen days in the 
summer to one hundred and eighty days beginning in the fall. The 
conditions essential to development and hatching are moisture, such as 
sup]")lied by sufficient atmospheric humidity to prevent eggs losing 
moistiu'e by evaporation, and a favorable temperature. 

The hatching period is taken as the time required for all of the eggs to 
hatch after hatching begins, the eggs deposited by a female hatching 
approximately in the sequence in which they are laid. The average 
period was found to range from ten and six-tenths days for July to 



THE TICKS 



149 



thirty-six days for October. The maximum period observed was forty- 
nine days for October, the minimum four days for July. 

The longevity period is stated to depend on individual vitality, 
hiunidity, and temperature. It was noted, especially in eggs laid during 
the winter, that some larvae do not have sufScient vitality to disengage 
themselves from the eggshell and die partly inclosed within it ; also that 
others die very soon after emerging. Cold, it is stated, prolongs longev- 
ity because of the fact that the tick remains quiescent with resulting 
conservation of body fluids and nourishment. The fact that the larvae 
respond negatively to light is an additional factor promoting longevity. 
In places exposed to the sun they collect on the under side of leaves and 
other vegetation, thus protecting themselves from loss of body moisture 
through the direct heat of the sun. In observations made it was deter- 
mmed that the average maximum longevity for larvae hatched from a 
number of lots of eggs in July was thirty-eight and six-tenths days. 
From eggs hatched in October the average maximum period was one 
hundred and sixty-seven and four-tenths daj^s. The shortest period 
was four days for larvae hatched in July, the longest two hundred and 
thirty-four days for larvae hatched ua October. 

The following summaiy is given of the data on the nonparasitic 
period : 

Total Time from Dropping of Female until all Resulting Larvm are Dead 



Date engorged 

females were 

collected 


Number 

of engorged 

females 


Range of 
entire- 
lime 
periods 


Average 

of 
periods 


Dale engorged 

females were 

collected 


Number 

of engorged 

females 


Range of 
entire- 
time 
periods 


Average 

of 
periods 


June 1, 1907 


7 


Days 
79-"l00 


Days 
86.9 


Dec. 29, 1907, 

to 
Jan. 1, 1908 


3 


Days 
181-207 


Days 
196.3 


July 1, 1907 


• 7 


82-112 


101 


Jan. 29 to 
Feb. 4, 1908 


7 


156-189 


173.1 


Aug. 1, 1907 


7 


172-221 


199.6 


Feb. 27 to 28, 
1908 


2 


143-162 


152.1 


Aug. 31, 1907 


6 


230-272 


250.7 


Mar. 26 to 
29, 1908 


9 


144-161 


152.1 


Oct. 1, 1907 


7 


276-288 


279.6 


April 29, 
1908 


14 


122-173 


142.8 


Nov. 1, 1907 


7 


200-253 


232.7 










Nov. 30, 1907 


3 


187-249 


217 











The Parasitic Development. — The parasitic development has three 
stages, the larval, the nj-mphal, and the adult. In the experiments car- 



150 



PARASITES OF THE DOMESTIC ANIIVIALS 



ried on upon this portion of the tick's life histoiy tick-free animals were 
infested at nine different times from July, 1907, to May, 1908. It was 
found that the minimum larval period ranged from five to seven days; 
the minimum njinphal period of females, nine to eleven days ; the adult 
period, from a minimum of five to a maximum of thirtj'-three days. 
The table which follows is given to show the range of the periods ob- 
served upon larvae which were marked after they had become attached 
and then kejDt under observation from dav' to day. 



Length of Period and Total Duration of Parasitic Development 



Date larvce applied 


Sex 


Length 

of larval 

period 


Length 

of nymphal 

period 


Length 

of adult 

period 


Duration 

of parasitic 

period 


1908 
Feb. 29. . ... 


Females 


Days 

8-9 


Days 
10-15 


Days 
5-13 


Days 
25-34 






Do 


Males 


7-9 


8-10 


— 








Do 


(?) 


7-14 


— 


— 


— 


April 4 . . . 


Females 


7 


9-14 


4-9 


25-26 






Do. 


Males 


7 


8-12 


— 








May 23 


Females 


6-7 


9-12 


6-9 


22-25 






Do 


Males 


5-8 


8-13 


— 


— 



As to the importance of the foregoing data, Graybill saj's: "The dura- 
tion of each of these stages and the duration of a single infestation upon 
cattle during different portions of the year are of great jDractical im- 
portance. Upon the duration of an infestation depends the time anmials 
must be kept on tick-free fields ui order to become free from the ticks." 



THE TICKS 151 

Life Histories of the Dog Tick and Texas-Fever Tick Compared 
IN Tabular Review (note italics) 

dermacentor variabilis 
Ovigerous Female. — Engorges upon host, drops to ground, 
I and deposits eggs. 

Eggs. — Deposited upon ground in mass. 

Larvse. — Bunched upon grass from which they reach 
I first host. 

First Molt, Larvse to Nymphs. — Upon ground, after drop- 
I ping from first host. 

Nymphs. — Crawl from grass upon second host. 

~\ 
Second Molt, Nymphs to Adults. — Upon ground, after 

I dropping from sec- 

I ond host. 

Males and Females. — Crawl from grass upon third host; 
I mate. 

Ovigerous Females. — Engorge upon host. 

Ovigerous Females. — Drop to ground and deposit 
eggs. 

MARGAROPUS ANNULATUS 

Ovigerous Female. — Engorges upon host, drops to ground, 
I and deposits eggs. 

Eggs. — Deposited upon ground in mass. 

Larvse. — Bunched upon grass from which they reach 
I host. 

First Molt, Larvse to Njonphs. — Upon host. 

Second Molt, Nymphs to Adults. 

Males and Females. — Upon host; mate. 

\ 
\ Ovigerous Females. — Engorge upon host. 

~ \ 

Ovigerous Females. — Drop to ground and deposit 

eggs. 

Loss Occasioned by Cattle Ticks. — According to estimates published 
in 1914, the main sources of loss occasioned by the cattle tick may be 
summarized as follows: 



1.52 PARASITES OF THE DOMESTIC ANIMALS 

The parasitic life of the ticks, together with the blood-destroying 
properties of the protozoan parasites with which they inoculate their 
hosts, causes a loss of flesh and lack of development in southern cattle 
conservatively estunated at $23,250,000. 

The lower price which southern cattle from infested districts bring 
in northern stockyards averages at least .$1.50 per head. It is estimated 
that the loss upon animals marketed under these conditions, including 
stock, beef, and dairy cattle, will sum up to $1,057, .500 annually. 

The shiinkage in milk production of cattle infested with many ticks 
will average about one quart per day. Upon an estimate of 875,000 
ticky dairy cattle out of more than 4,000,000 daily cattle below the 
quarantine line, the loss thus occasioned, reckoned at three cents per 
quart, would amount to $26,250 per day, or, counting three hundred 
milking days for each cow to the year, $7,875,000 annually. 

The loss among noninunune southern cattle m tick-free pastures 
through contracting Texas-fever when exposed to the tick has been 
estimated at .$5,812,500 per annum. 

The deaths from Texas-fever of pure-bred or high-grade cattle im- 
l^orted from the North for breeding purposes amount to about sixty 
j3er cent, among such cattle which have not been innnunized by blood 
inoculations, and to about ten per cent, among those which have had 
such imnnmization. Since these are usually expensive anmials, the 
loss in .such cases is often excessive. 

Considering additional losses, direct or indirect, as published by the 
United States Department of Agriculture in 1914, it will be found that 
the Texas-fever tick is responsible for a loss of about .$40,000,000 an- 
nually, in addition to which it is responsible for lowering the assets of 
the infested country to the extent of $23,2.50,000. 

Progress in Eradication. — Methods of dipping and pasture rotation 
for the control of the cattle tick have been fully set forth in bulletins 
and circulars iniljlished by the United States Department of Agriculture 
(Farmers' Bull. No. 498). The.se are freety available to all interested in 
details of the subject which need not be repeated upon these pages. 

Eradicati\-e measures carried on I)}' the Federal Government in 
cooperation with the states affected by the cattle tick have seen in 
))rogress since 1906. Up to 1911 twenty per cent, of the infested area, 
mostly along the northern boundar.y, had been cleaned through this 
systematic cooperative work. At the present time (1918), through the 
continuation of this work, fifty-two per cent, of the tick-infested area 
has been released from qtiarantine, and it is authoritatively predicted 
that five j'cars hence the cattle tick will be entirely eradicated from the 
South. 



THE TICKS 

OhDER II. LiNGUATULIDA 



15S 




adult (after 
5, Bureau of 



Arachnida (p. 94). — The members of this group are arachnids which 
have become extremely altered in consequence of their parasitic mode 
of life. Due to their worm-like body and endoparasitic habits, they were 
formerly placed with the helminths. 

The body is elongated, annulated, and somewhat flattened. The 
body regions are not defined from each other. With the exception of 
two pairs of articulated hooks 
surrounding the mouth, re- 
garded by some as vestigial 
legs, the adult body is entirely 
without appendages (Fig. 83). 

The mouth is anterior, and 
the intestine passes directly 
through the body, opening by 
the posterior anus. 

There are no circulatory or respiratorj^ organs 
general surface of the body. 

The nervous system is reduced, consisting of the esophageal ring, 
which gives off filaments to the cephalothorax region. Eyes are absent. 

The sexes are separate; the male much smaller than the female. From 
the eggs there hatches an ovoid embryo, constricted at its posterior 
extremity, and provided with two pairs of jointed legs. Anteriorh^ it 
has a perforating apparatus by means of which it bores through the 
intestmal wall of its host and reaches the liver, or other organ, in which 
it becomes encysted. 

The adult Linguatula {L. rhinaria) infests the nasal cavities of mam- 
mals, usually the dog. The larvae infest the visceral organs of herbivor- 
ous anunals. 



Fig S3. — Linguatula rhinaria, 
Osborn, from Packard; Bull. No. 
Entomology, U. S. Dept. of Agr.). 



Respiration is by the 



PART II 
THE INTERNAL PARASITES 

CHAPTER XIV 

PHYLUM II. PLATYHELMINTHES. THE FLUKES AND 
TAPEWORMS 

With but few exceptions all of the metazoan internal parasites come 
into the old division Vermes, which brings together animals generally 
worm-like, though widely differing in many respects. Compared thus 
as a whole with animals usually rated below them in the zo5logical 
scale, worms are readily distinguished in possessing differentiated 
anterior and posterior extremities, the anterior directed toward their 
forward movement and involving a head which contains a ganglionic 
mass of nerve cells or, as it may be called, a rudimentary brain. Fur- 
thermore, the body is bilaterally similar, and there is a dorsal and 
ventral surface. The annulated worms, which include the higher 
representatives, differ from the Arthropoda mainly in the absence of 
articulated appendages to their body-segments, while the lack of a 
notochord and gill-slits distinguishes them from certain lowly members 
of the Chordata. Beyond these few points there is little to be said as 
to the characteristics of the worms considered as a whole. 

The including in a single phylum of all invertebrates generallj^ elongate 
and without articulated appendages is systematically faulty in that it 
brings together animals with structural differences of grand division 
importance, though agreeing in an external form generally worm-like. 
In most of the present-day systems of classification the worms are dis- 
tributed into three, or at least two, phyla, the older class division 
Platyhelminthes, or flat worms, being given grand division distinction. 
Many authors also place the smooth-bodied Nemathelminthes and the 
annulated worms in separate phyla, while another division, — the 
Molluscoidea, has been created to dispose of the more or less related 
moss-like Polyzoa (Bryozoa) and the mollusc-like Brachiopoda. An 
objection to such arrangement is that groups poor in species, some of 
them mainly of parasitic interest, are placed on the same basis as such 
large and very imjiortant divisions as the chordates and arthropods, 
thus giving them an undue prominence in a general consideration of the 
animal kingdom. 



156 PARASITES OF THE DOMESTIC ANIMALS 

The classification adopted here places the smooth roundworms and 
the annulated worms together in the phylum Ccelhelminthes, an ar- 
rangement based upon the presence of a coelom or bodj' cavity, which 
is a structural feature clearly defining these worms from the Platyhel- 
minthcs and establishmg a relationship between the smooth i-ound and 
annulated forms of primaiy importance. 

The Platyhelminthes includes worms which are flattened dorsoven- 
trally, the two surfaces luiiting in more or less sharp margins. There is 
no body cavity, the various organs being embedded in a mass of con- 
nective tissue and muscle fibers. The alimentary tract is a simple or 
bifurcated, sometimes branching, pouch having no anal opening (Fig. 85), 
the mouth serving as both inlet and vent. In some parasitic 
forms (tapeworms) alimentarj- organs are entirelj' wanting. 
A true circulatory sj'stem is absent. There is a series of ex- 
cretoiy tubes which ramify throughout the bod}', usually 
opening to the outside near the posterior extremity. The 
nervous system consists of ganglia located above the esoph- 
agus, where this is present, and the lateral nerves which these 
Planal-lan^ give off. Most all are hermaphroilitic, the sexual organs 
worm (after being distributed over a large portion of the body. 
Orton, by \s js, {y^Q of the womis in general, free living forms are 
rightT 1894^"^''""'' '" fresh and salt water. They may often be revealed 
by Harper & clinging to the under side of rocks (planaria, Fig. 84) and 
Brothers). upon the moist soil, some of these specimens being nearly 
ti'ansparent. The largest members of the division are the tapeworms 
which may reach a length of thirty feet or more. 

The phylum contains two parasitic classes, as follows: 
Class I. Trematoda. — The flukes. 
Class II. Cestoda. — The tapewonns. 

CL.4.SS I. Trematoda 

Platyhelminthes (p. 156). — All of the members of this group are 
parasitic, living either as ecto- or entoparasites. The body is usually 
leaf-like, often much like a pumpkin seed in form (Fig. 87), and is pro- 
vided anteriorl.v with suckers by which attachment is made to the host. 
In most of those entoparasitic (Distomese) two suckers are present, one 
anterior and surrounding the mouth, and a second larger one just 
posterior to the mouth on the mid-ventral line. In the ectoparasitie 
species (Polystomcae), which are usually parasitic upon the gills and 
skin of acjuatic animals, the .suckers are more numerous. 

The alimentary tract leads by a short gullet to a bifurcation, forming 
two elongated blind sacs which may or may not give rise to lateral 
secondary pouches (Fig. 85). Eye spots occur in some of the ectopara- 
sitie species and in the larvse of the entoparasitic. 



PLATYHELMINTHES 



157 



Most of the Trematoda are hermaphroditic. At maturit}^ the sexual 
organs reach a high degree of development adaptive to the mode of 
parasitism (Introduction,- p. 5). The male sexual organs consist of 
tube-like testes, from which spermatic ducts take origin. These unite 
in a large seminal vesicle, the termmal portion of 
which is usually inclosed in a pouch. The ovarj' 
is also branching and tube-hke. With the oviduct 
there unite ducts from the vitellaria or yolk-glands, 
this union being followed by the much convoluted 
uterus which receives the eggs and terminates bj' 
the side of the male sexual opening (Fig. 86). 

The entoparasitic trematodes undergo a compli- 
cated life history, involving alternation of hosts 
and, within the intermediate host, multiplicative 
generations. A typical example of this cj^cle is 
given further on in reference to the species Fasciola 
hepattca. 

Most of the trematode parasites of mammals 
live in the liver, producing the affection known as 
hepatic fascioliasis (distomiasis), or commonly as 
liver rot. Others invade the blood, lungs, and 
stomach, causing, accordingly, vascular, pulmonary, 
and gastric fascioliasis. The latter forms are rarely 
met with in the United States.' 

The species to be considered come under three 
famihes, as follows: 

Family I. Fasciolidje. — The common liver flukes. 

Family II. Amphistomidse. — Of the rumen. 

Family III. Schistosomidfe. — The blood fluke. 




Fig. 85.— Sketch of 
Fasciola hepatica, 
shot^Tug bifurcated and 
branching alimentary 
tract; si, mouth and 
anterior sucker; s2, 
posterior sucker; t. a., 
alimeutarj- tract, — en- 
larged (after Boas, by 
Kirkaldy and Pollard, 
from Thomas). 



Classificati6n of Parasites o.f the Phylum Platyhelminthes 

Phylum II. Platj'helmmthes. P. 155. 
Class A. Trematoda. Flukes. P. 156. 
Order 1. Distomeis. P. 156. 
Family (a) Fasciolidse. P. 160. 
Genus and Species: 

Fasciola hepatica. Hosts, sheep, cattle, etc. P. 160. 
Dicrocoelium lanceatum. Hosts, same. P. 160. 
Fasciola americanus. Hosts, same. P. 160. 
Family (b) Schistosomida?. P. 168. 
Genus and Species: 

Schistosoma bovis. Hosts, cattle, sheep. P. 168. 
Family (c) Amphistomidte. P. 167. 



158 PARASITES OF THE DOMESTIC ANIMALS 




Fiii. 86. — RopnidiK'tive organs of liver fluke: f, female aperature; s. v., seminal vesicle ; 
y. g. 1.. diffuse yolk elands; sh. g., shell gland; v. d., vas deferens; T., testes; ov, ovary 
(dark); ut, uterus; r'. s., cirrus sac; p, penis; m, mouth; g, anterior lobes of gut (after 
Thomson, from Srjninier). 



PLATYHELMINTHES 159 

Genus and Species: 
Amphistomum cervi. Hosts, ruminants. P. 167. 
Class B. Cestoda. Tapeworms. P. 169. 
Order 1. Polyzoa. 

Family (a) Tseniidse. P. 170. 
Genus and Species: 
Anoplocephala perfoliata. Host, equities. P. 174. 
A. mamillana. Host, equines. P. 175. 
A. plicata. Host, equines. P. 175. 
Moniezia expansa. Hosts, cattle, sheep, goats. P. 176. 
M. alba. Hosts, same. P. 176. 
M. planissima. Hosts, same. P. 176. 
Thysanosoma actinioides. Host, sheep. P. 176. 
Dipylidimn caninum. Hosts, dog, cat, man. P. 178. 

Larva, Ciyptocystis trichodectes. Hosts, flea, louse. 
P. 178. 
Taenia hydatigena. Host, dog. P. 178. 

Larva, Cysticercus tenuicollis. Hosts, ruminants and 
hogs. P. 179. 
T. pisiformis. Host, dog. P. 179. 

Larva, Cysticercus pisiformis. Host, rabbit. P. 179. 
T. ovis. Host, dog. P. 204. 

Larva, Cj'sticercus ovis. Host, sheep. P. 203. 
Multiceps multiceps. Host, dog. P. 179. 

Larva, Multiceps multiceps. Host, Herbivora. P. 179. 
M. serialis. Host, dog. P. 179. 

Larva, Multiceps serialis. Hosts, rabbit and other 
rodents. P. 180. 
M. gaigeri. Host, dog. P. 181. 

Larva, Multiceps gaigeri. Host, i-mnmants. P. 181. 
Echinococcus granulosus. Hosts, dog, cat. P. 181. 

Larva, Echinococcus granulosus. Hosts, ruminants, hog, 
etc. P. 181. 
Taenia tasniseformis. Host, cat. P. 184. 

Larva, Cysticercus fasciolaris. Hosts, rat, mouse. P. 184. 
Cittotaenia denticulata. Host, chicken. P. 185. 
ChQanotsenia infundibuliformis. Host, chicken. P. 189. 

Larva, a cysticercoid. Host, house fly. P. 189. 
Hjinenolepis carioca. Host, chicken. P. 190. 
Davainea tetragona. Host, chicken. P. 190. 
D. cesticillus. Host, chicken. P. 190. 
D. echinobothrida. Host, chicken. P. 191. 
D. proglottina. Host, chicken. P. 191. 
Larva, a cysticercoid. Host, snail. P. 191. 



160 PARASITES OF THE DOMESTIC ANIMALS 

Tajiiia saginata. Host, man. P. 195. 

Larva, Cysticercus bovis. Ho.st, ox. P. 195. 
T. solium. Host, man. P. 199. 
Larva, C.vsticercus cellulosse. Host, hog, etc. P. 199. 
Family (b) Dipliyllobothriidre. P. 185. 
Genus and Species : 

Diphyllobothriuni latum. Hosts, man, dog, cat. P. 185. 
Larva, a plerocercoid. Host, fish. P. 185. 



Family I. Fasciolid.e 

1. Fasciola hepatica (Distomum hepaticum). The Liver Fluke 

(Fig. 87). Trcinatoda (p. 156). — The liody is flattened, pale brown in 
color, oval in shape, and broadest m front, where it is terminated by 
a conical process bearing at its apex the oral sucker which surrounds 
the mouth. A larger ventral sucker is situated about 3 mm. behind 
the oral. The cuticle is studded with minute spines directed back- 
ward. The bifurcations of the alimentary tract have ramifj-ing 
branches. The vulva is situated beside the male opening or a little 
liehind it. 

Length, 20-30 mm. (H-IH inches); width, 10-13 mm. (Vs-M an 
inch). 

The eggs ar(> blown or greenish-yellow, ]:)rovided with an operculum 
at one end. They are oval and 130-145 microns in length. 

2. Dicrocoelium lanceatum (Fasciola lanceolata). The Small Liver 
Fluke (Fig. 87). Trematoda (p. 156). — The body is slender and 
!ancet-sha|)ed, mottled brown by contained ova. The integument is 
smooth and semi-transparent. The intestine has two nonramifying 
branches. 

Length, 4-9 mm. (3/16-3/8 of an inch); width, 2.5 mm. (1/8 of an 
inch). 

The eggs are oval, l)rownish in color, 37-40 microns in length, and 
provided with an operculum. 

3. Fasciola magna (F. americana, Distomum americanum, D. mag- 
num). The Large American Liver Fluke (Fig. 87). Trematoda 
(p. 156). — Similar to F. hepatica, but lai'ger, measuring 25-33 mm. 

width. 

Life History of Fasciola hepatica. — The eggs leave the uterus be- 
fore the beginning of embryonic development and pass to the outer 
world by way of the bile ducts and intestines. In heavy infestation 
enormous numbers may be passed hy a single host animal, one mature 
tiuke producing in the neighborhood of one hundred thousand eggs. 



PLATYHELMINTHES 



161 




Fig. 87. — Left to right, Fasciola hepatica, 
F. americanus, Dicroccelium lanceatum: 
natural size (drawn from author's speci- 
mens) . 



After a period of embryonal development, which will onh- occur pro- 
viding the eggs have reached water and suitable conditions of tempera- 
ture, the larva escapes by the lifting of the' operculum of the shell. It 
is then in the stage of the miracidium (Fig. 88, 2j, an infusorian-like 
organism, ciliated, elongated, broader in front, and about 130 microns in 
length. During its free-swimming period it must meet with a suitable 
host within a few hours or it will perish. This host is a small snail, 
usually of the genus Limnsea (L. 
humilis) into which the larva 
bores its way by a perforating 
rostnim at its anterior extremity. 

If it escapes its aquatic enemies 
during this free stage and arrives 
at a suitable location within the 
snail, usually the pulmonary 
chamber, the larva loses its cilia 
and digestive tube and becomes 
transformed into a sporocyst (Fig. 
88, 3) — a sort of reproductive sac, 
ovoid in form and acquiring a 
length of about 0.5-0.7 mm. The 
■cyst now becomes filled with germ-cells which are disposed in masses 
(morula) ordinarily five to eight m number. 

The masses of germ-cells become transformed into so manA' redice 
(Fig. 88, 5 and 6) which may be seen in different stages within the cj^st. 
The rediiE are cylindrical in form and have a simple intestiiae and 
pharynx with lips turned out like a sucker. When thej^ have attained 
a certain stage of development the redise becoine actively motile, finally 
rupturing the maternal cyst and passing to another organ of the snail, 
usually the liver, in which location they grow to a length of 1.3-1.6 mm. 
Within the body of the redia are germ-cells formed into six to ten cellular 
masses which are to be transformed into so many daughter redise, or 
directly into fifteen to twenty cercaricB (Fig. 88, 7). Both daughter 
redise and cercarise leave the mother redia by a birth-opening located 
anteriorljr. 

The developed cercaria has an oral and ventral sucker, a muscular 
pharynx, and\ a bifurcated intestine which is as yet without lateral 
branches. It has a flat oval body about 0.28 mm. in length, provided 
with a long actively vibratile tail. The cercarise escape from the snail 
and swim about energetically in the water, eventually findmg their way 
to an aquatic plant or grass stalk. Here the tail is lost and the cystoge- 
nous cells of the body form a mucoid substance which serves both to 
encyst the cercarise and to attach them to the grass. The cysts maj^ be 
observed upon the specimens of vegetation as little white points about 



162 



PARASITES OF THE DOMESTIC ANIMALS 



the size of an or(li)uir>- ijin-head. .\n encysted cercaria will remain alive 
for an extended period as long as the jirass tipon which it is lodged is 




Fig. 88. — Life history of liver fluke: 1, egg containing de- 
veloping embryo; 2, free swimming miracidium; 3, sporocyst; 
3a. snail of the genus Limnaea; 4. division of sporocyst; 
5. sporocyst containing developing rediae; 6, redia with cer- 
caria or more redite developing within it; 7, cercaria; 8, young 
fluke (after Thomson, from Thomas). 

supplied with nioistin'e. Drought probably destroys it, though the 
length of time it may survive such conditions is undetermined. 
AVhen jilants bearing these cysts are eaten by grazing animals the 



PLATYHELMINTHES 163 

cysts, upon reaching the stomach, are dissolved, setting free the par- 
asites which, passing to the intestine, enter the bile ducts and there 
become mature. After laying their eggs the majority of the flukes pass 
down the bile ducts to the intestine where, under the mfluence of the 
digestive juices, they shrivel and die. 

The period of time occupied by the entire cycle is so influenced by 
climatic conditions that no definite estimate as to it can be given. 
As a rough approximation, twelve weeks may be given as about the 
time required under such favorable conditions as usually prevail during 
the summer season. 

The life histories of Dicrocodium lanceatum and Fasciola magna are 
probably essentially similar to that of F. hepatica, but are as yet not 
definitely known. 

Tabular Review of Life History of Fasciola Hepatica 
Adult Fluke. — In bile duct of liver of ruminant. 

\ 
Egg. — Free. 

Miracidium. — Free. 

Sporocyst. — In pulmonary chamber of snail. 

Sporocysts 5 to 8 Rediae. 

f I 
Rediae. — In hver or other organ of snail. 

i I 

Daughter Redise 15 to 20 Cercariae 

I [ 
Cercarise. — Free. 

\ 
Cysts. — Upon grass stalks or other vegetation. 

Adult Flukes. — In bile duct of Hver of ruminants after 
ingestion of cysts. 

Prevalence. — The loss from hepatic fascioliasis in England was for 
a time in the neighborhood of three million head of sheep annuallv. 
It was principally for this reason that investigations were made by 
which the life histoiy of the parasite was determined, and by which 
was revealed the essential alternation between the sheep and snail 
host. This pointed the way for measures of control consistmg mamly 
in the elhnmation of snails by the drauiage of pastures or in the limiting 



164 PAEASITES OF THE DOMESTIC ANIINIALS 

of the sheep to pastures free from standing water or overflow. Since 
the adoption of such preventive measures the loss from this source in 
England and other European countries has been greatly reduced. 

While fascioHasis has not been as prevalent in the United States as in 
Europe, there are a sufficient number of cases to demonstrate the pos- 
sibility of its becoming so imless such precautions are taken as are in- 
dicated by the life history of the fluke. Probably the freedom from such 
destnictive prevalence has been largely due to the fact that m this 
country, more generally than m Europe, it is the practice to turn sheep 
upon higher and dryer pasturage. 

The three species of flukes wliich have been mentioned infest the 
liver, therefore the hepatic form of fasciohasis is the most important. 
As would be concluded from the mode of infection, herbivorous animals 
are most often affected, those which crop the grass close to the ground, 
as sheep and goats, beuig for this reason especially susceptible. Horses, 
swine, Carnivora, and even man may be invaded incidentally by flukes, 
though in such cases they are rarely present in such numbers as to produce 
perce|itiblp disturbance. The giant fluke (Fasciola magna) is most often 
found m the liver of deer or cattle in the Southwestern portion of the 
United States. It is supposed to be a species native to wild ruminants 
before the introduction into this country of those in domestication. 

Infection. — While infestation of sheep most frequently occurs from 
the ingestion of plants upon which the encj'sted cercariiE are attached, 
water contaminated with detached cercariae may infect directly, or by 
vegetation over which it has washed. It is probable that many cases 
in cattle in the United States result from the introduction of the flukes 
by tiie latter means. Cattle are not as close grazers as sheep, but they 
drink more frequently, often from shallow collections of water which 
may contain larvae derived from the excrement of sheep or rabbits. 

As man}- encj-sted cercarise survive the frosts even of the late fall, 
the season during which infection may take place is somewhat extended, 
some investigators claiming that it mav' occur at any time of the year. 
However, warmth being highly favorable to the development of the ova, 
it is essentially during the summer and early autumn that animals are 
most likely to become mvaded. It is obvious that the most numerous 
and most severe cases would occur in seasons of copious rainfall, more 
ele\-ated pastures at such times affordmg by their collections of water 
and OA'erflow favorable conditions for the development of the parasites. 
The flukes may be introduced into lands previously free from them 
by new stock, or by wild herbivorous animals, such as deer and rabbits. 
After infestation has once taken place, it will, through successive in- 
fections, mcrease in degree the longer the pasture is used. 

Migrations and Pathogenesis. — It is probable that the migration 
of the parasites from the small intestine into and along the bile ducts 



PLATYHELMINTHES 165 

is accomplished by the extending forward of the parasite's anterior 
end, with alternate fixing of the oral and ventral sucker. The majority 
remain in the bile ducts, though some upon reaching the smaller ducts 
break through and pass into the liver tissue where they may excavate 
and destroy large areas. Such migrations may extend thi-ough GHsson's 
capsule to the serous covering of the organ and thus give rise to pei- 
itonitis in addition to the inflammation of the hepatic parenchyma. 
They do not essentially remain confined to the liver, but maj' pass 
through the capsule and serosa into the peritoneal cavity. Others may 
reach the ramification of the portal vein and set up an endophlebitis 
with accompanymg thrombosis and embolism ; or the hepatic veins may 
be involved and some flukes be carried by the blood current to the 
thoracic organs. 

The destruction of liver tissue in hepatic fascioUasis is largely the 
result of direct irritation due to the spiny processes covering the par- 
asites. During the first few weeks after being taken up by the host the 
flukes are small and do not cause a serious irritation. Later they set 
up an acute inflammatory condition of the bile ducts and fiver tissue, 
the hepatitis remaining more or less localized or becoming generaHzed 
according to the number of parasites present and the extent of their 
migrations. In certain cases there is abscess formation, or hemorrhages 
may occur due to the breaking down of the walls of blood vessels. The 
inflanmiation running a chronic course is associated with connective 
tissue prohferation, causing a thickening of the walls of the ducts. Later 
this process extends to the interlobular connective tissue and brings 
about cirrhosis of the liver. 

Flukes which have remained in the bile ducts pass back into the 
duodenum soon after the reproductive function has been accomphshed. 
It is thought by certain investigators that the period of tinie which 
they remain in the ducts does not exceed nine to twelve months. Within 
the intestines they are much altered by the intestinal juices and pass 
from the host with the excrement. 



Fascioliasis of Sheep 

Symptoms and Course. — An animal harboring but few flukes will 
give no evidence of functional disturbance. This can be readilj^ dem- 
onstrated in sheep-slaughtering establishments where moderately in- 
fested livers have been repeatedly found in sheep in prime condition. 
In heavier infestations a developing period of about three to six weeks 
intervenes between the taking up of the flukes and the appearance of 
symptoms. 

In sheep usually the first s\anptoni to be noticed is dullness, man- 
ifested by slowness of movement and an inclination to lag liehind the 



16() PARASITES OF THE DOMESTIC ANIMALS 

flock. On examiiiation of the visible mucosse (conjunctiva) and inner 
surface of the ears they will be found to be paler than usual, and there 
may already be edematous swelling of the eyelids and under the brisket. 
Notwithstanding the ansemia, the general physical condition of the 
animal ma.y .still be good; there is, in fact, a tendency to fatten, which 
may be explained physiologically in the increased assimilation of the 
fat-forining elements of the food, brought about by the stimulation im- 
parted bj- the flukes to the flow of bile. 

This stage, however, is soon followed by a marked increase in dullness 
and a disinclination to take food. The animal ruminates slowly and 
irregularly, the fleece becomes dry and brittle, and in places may loosen 
and tlroj) out; the skin and mucosae are whitish-yellow in color, the puffy 
conjunctiva forming a prominent ring about the cornea. Though the 
sheep nuiy still be fat, weakness and disinclination to resist handhng 
l)ecome more pronounced. With piogressively diminished appetite, 
ho\ve\'er, there is loss of flesh, and the edema of the dependent parts 
increases, involving the lower ]^art of the neck, throat, and cheeks. The 
presence of ascites is evinced ujion peicussion of the pendulous al)domen, 
and the respii'ation becomes labored and frequent. 

With these .symptoms, which genei'ally appear about the third month 
after infestation, the disease is at its maximum, usually reached in the 
early winter months. The anaemia, edema, and cachexia have now 
become more pronounced; in most of the advanced cases there is diarrhea 
by which large mmibers of eggs may be distributed about. Finallj', 
in a condition of extreme emaciation and weakness, the animal dies. 

Prognosis. — Most of the losses from fascioliasis of sheep are among 
the lambs. Older animals and those but moderately infested graduaU.y 
i-eco\'er with the passage of the flukes fi'om the liver into the intestine, 
this usually occuri-ing in the early spring. With the disappearance of 
the edematous swellings and the return of the appetite, the animal re- 
svnnes a good physical appearance and seems to completely recover. 
The liv(>r lesions, however, will not entirely heal, and, impairing the 
function of the organ, will eventually have a deleterious effect upon 
the animal. 

F.\.SCIOLIA.SI,S OF C.\TTLE 

In cattle fascioliasis presents the same symptoms as in sheej). Due 
to the greater resistance of these animals, however, the effects are much 
less severe and may often pass unperceived. If the flukes are numerous 
there may be digestive disturbances manifested by loss of appetite, 
diarrhea, and tympanites; very rarely there are edematous swelHngs in 
the dependent parts of the body. Fatalities from fascioliasis are rare 
among cattle. A^'hen Uwy occur it is usually among calves which have 
reached an advanced emaciation. 



PLATYHELMINTHES 167 



Family II. Amphistomid^e 

Amphistomum cerui (A. conicum) is a species Ijelonging with tiiis 
family not infrequently found in the rumen of domestic ruminants of 
this and other countries. Specimens collected in the Pennsjdvania State 
Laboratory measure 6 to 7 mm. (3/16 to 1/4 of an inch) in length. The 
body is conical in form, thick, attenuated anteriorlj^, gradually en- 
larging posteriorly, the posterior end being obtuse and a little curved 
ventrally. The mouth is terminal and surrounded by a small sucker. 
At the thickened posterior extremity there is a second and much larger 
sucker. The color is white or reddish, darker at the attenuated anterior 
portion. Hermaphroditic; genital orifices ventral and median, situated 
in the anterior third of the body. Its development is not known. 

This fluke is a parasite in the rumen of the ox and other domestic 
and wild ruminants. It fixes itself by means of its posterior sucker 
between the papillae of the rumen. Being very easily overlooked in its 
resemblance to the papillse, it is quite probable that it is more prevalent 
than would appear from our present records. 

The parasite has been considered as inoffensive to the health of the 
host animal. 

CONTBOL OF FaSCIOLIASIS 

In sections where fascioliasis has appeared a prophylactic measure 
of first importance is the avoidance of pastures which are wet or contain 
collections of water affording habitation for snails. The following direc- 
tions formulated by Thomas — as stated bj^ Neumann — for limiting the 
ravages of fascioliasis are here quoted in part: 

"a. Destroy' the diseased sheep and bury them. 

"b. Only put on dry pastures affected sheep intended for the butcher, 
as the fluke ova thej^ evacuate cannot develop in the absence of humidity-. 

" c. As hares and rabbits — whjch are sometimes beai'ers of distomes — 
may infest pastures, they should not have access to those on which 
sheep graze. But this recommendation cannot well be carried out. 

"d. Drain wet pastures, or, if this cannot be accomplished, dress 
them with salt or lime. The latter in solution — 0.75 per cent. — will 
destroy fluke embryos as well as the snails. With regard to salt, we are 
indebted to"^ Perroncito for some precise notions as to its action. Erco- 
lani had for a long time observed that water slightl.v impregnated with 
salt killed the cercarite, and in acting on these and on the encysted 
larviB of the Limncea palustris. Perroncito found that in a 2 per cent, 
solution these parasites died in less than five minutes; in a 1 per cent, 
solution they rolled themselves up at the end of two to seven minutes, 
and perished after twenty to thirty-fi^'e minutes. The same hapi^ened 
in 0.64 per cent, solutions; and in those of 0.25 per cent, they were still 



168 



PARASITES OF THE DOMESTIC ANIMALS 



alive after more than twenty hours. The period when salt or lime 
should be spread on the pastures should coincide with the time when 
the embryos of the distomes and the cercarise abound — that is, June 
and July for the first, and August for the second." 

If it is impracticable to keep sheep from land upon which conditions 
are favorable for the development of flukes, they should each be given 
in the moi-ning daily two drams of salt mixed with feed. When possible, 
the salt may also be given in their drinking water in the proportion of 
0.5 per cent. -The salt is fatal to the ingested cercarise and tends to 
fortify the sheep by favoring digestion and assimilation. 

Treatment. — No effective therapeutic agent for fascioliasis has as 
j'et been found. Owing to the remote location of the parasites, it is 
hardly likely that anything could be given which would affect them. 



BlLHARZIOSIS 

This name has been given to a disease of cattle and sheep caused by 
the blood fluke Schistosoma bovis {Bilharzia bonis; B. crassa) of the family 
Schist osomida". 

In this trematode (Fig. 89) there is presented the peculiarity of sep- 
arate sexes. The female, longer and much nar- 
rower than the male, is. filiform, 18-20 mm. (^ 
of an inch) in length, and has a buccal and ven- 
tral sucker. The male is cylindrical, about 14 mm. 
(34 an inch) in length, and has two suckers. It 
carries the female in a ventral furrow formed by 
the two sides of the body which are broad and 
i-eflected inward. Both male and female genital 
apertures are situated immediately behind the 
ventral sucker. 

The eggs are elongate, and at one pole termi- 
nate in a pyriform point. They pass from the 
host with the feces and urine, and, in the presence 
of water, set free a ciliated embryo. 

This parasite has been found in the portal and 
abdominal veins of cattle of tropical and sub- 
tropical countries. The parasites themselves 
seem to do but little inji'uy. The eggs, however, 
by their accinnulation and sharp points, may 
rupture the capillaries. If these are of the 
genito-urinary system, the chief symptom is a bloody urine. Where 
the eggs have accumulated in the capillaries of the bladder, they rup- 
ture these and, passing through the mucosa, fall into the cavity of the 
organ. The resulting cystitis is manifested ))y the hsematuria and the 




Fig. >>9. — Schistosoma 
bovis, male and female, — 
enlarged. 



PLATYHELMINTHES 169 

pain which accompanies niicturation. If the parasites are contained 
in the veins of the rectum, there are similar lesions in this organ; the 
feces may be stained with blood, and there is a condition somewhat re- 
sembling piles. 

Diagnosis is best made by a microscopic examination of the urine 
to determine the presence of the eggs which may be readily recognized 
by their characteristic elongate shape and polar termination in a sharp 
point. 

As the lesions are produced by the eggs, the severitj^ of the symptoms 
will essentially depend upon the number of parasites present. In the 
majority of cases the infection is light and may give rise to no more than 
a slight chronic cystitis. In the more rare cases of severe infection death 
may ensue frora^'upture of the bladder or from ursemia accompanying 
an acute nephritis. A heavy intestinal infection may bring about an 
exhausting and fatal dysentery. 

It is probable that infection has its source in contaminated drinking 
water. Therefore, where bilharziosis has made its appearance, the water 
should, as a preventive measure, be filtered, or the cattle removed to an 
uncontaminated supplj^ 

Treatment can only be applied to the relief of SJ^nptoms as they 
appear. 

Class II. Cestoda 

Platyhelminthes (p. 156). — An important character of the cestodes 
is that, as a result of their advanced parasitism, they have lost the last 
trace of an alimentary canal, and obtain their nourislmient by absorp- 
tion through their integument of the partly digested food of the host. 
Also markedly distuiguishmg them are the two developmental stages, — 
the bladder worm (Fig. 112, b and c) and the mature worm (Fig. 107) 
with its sexually developed segments, the first living usually in tissues, 
such as muscular, fiver, nervous, and serous, of the intermediate host; 
the second m the alimentaiy tract of the definitive host. The adult is, 
in its general form, band-like, and consists of two parts, — the scolex 
(Fig. 109), which is generally referred to as the head, and a series of 
segments which are formed from the scolex asexually by longitudinal 
growth and transverse segmentation. It is due to this fact that an 
animal is not rid of its tapeworm so long as the head is retained in the 
intestine. As the segments are pushed on by the formation of younger 
segments at the scolex, they become progressively wider and longer, 
the width of the younger ones usually much exceeding their length, 
while the oldest, which are those most distant from the scolex, may 
become longer than wide. Each mature segment is hermaphroditic, 
the uterus usuall}^ containing a large number of eggs. In the Taeniidse 
the genital pores (sexual openings) are on the margin or margins of the 



170 PARASITES OF THE DOMESTIC ANIMALS 

individual sogineiits. In the Dipiiyllobotliriidae they are on the flat 
ventral surface. The number of segments varies fi'om three or four 
{Echinococcus granulosus) to several thousand {Diphyllohothrium latum), 
a fact which gives to some species an enormous size. In the head is a 
cerebral ganglion from which two principal nerves run backward, 
usually near the lateral margins of the segments. An excretory, or so- 
called water-vascular system, extends through the whole length of the 
worm by two principal trunks which maj^ be connected by vessels 
running across the posterior margin of each segment, the system ter- 
minating at the hinder edge of the last. 

Of the Cestoda, two families arc to be described as containing species 
parasitic to domestic animals and man. These are as follows: 

Family I. Tieniidse. 

Family II. Diphylloliothriidise. 

Family I. TiENiiD.E 

Cestoda (p. 169). — With rare exception, this family includes all of 
the tapeworms of domestic animals and man in the United States. Its 
nieml)ers have the head furnished with four round or oval cup-like 
suckers of muscular structure (Fig. 109), which, by their contraction, 
produce a vacuiun affording a close attachment to the intestinal nuicosa 
of the host. These suckers may .surround a prominence, — the rostellum 
(Fig. 95), or in other cases a depression more or less marked. The 
rostellum may or may not l)e contractile, and may or may not be armed 
with hooks. 

As a typical, though not constant, arrangement of the reproductive 
organs, those of the sjiecies Tmnia saginata, a tapeworm of man, are here 
described. Each .sexuallj' mature segment (Fig. 90) of this worm has 
at its margin a protruding genital pore, which, from segment to segment, 
is irregularly upon alternate sides. This protuberance contains a 
cloaca-like cavity into which open the vas deferens and vagina, both of 
which extend laterally to the middle of the segment. Here the vas 
deferens divides into a number of seminal ducts which are distributed 
through the supjiorting tissue and serve to carry the semen from the 
small spherical testes which are located almost everywhere in the seg- 
ment. As it appi'oaches the lateral cloacal sac, the duct becomes con- 
voluted and much distended with the accumulated seminal fluid. In the 
vicinity of the cloaca it develops into a cirrus (penis) which is inclosed 
in a nuiscular sheath. 

The vagina bends tlownward as it passes towanl the center of the 
segment where it unites with the paired wing-like ovaries which are 
rather large organs consisting of branched tubules. In the posterior 
and middle ]K)rtion of the segment is a single organ, likewise of branched 



PLATYHELMINTHES 



171 




tubular structure, — the viteUarium or .yolk-gland, the secretion from 
which surrounds the eggs in the cavity of the shell-gland, the latter a 
small bod}^ consisting of compactly arranged gland-cells and located 
just above the vitelline gland. From the shell-gland the eggs pass 
through a narrow duct into the uterus, a simple tubular organ ascending 
directly in the middle of the segment and closed at its distal end. The 
uterus becomes much dis- 
tended from the accumulation / i ( j 

of eggs and develops nu- 
merous lateral branches to 
which the other sexual organs 
gradually give place until lit- 
tle remams of them but ves- 
tiges of the vas deferens and 
vagina. The egg-engorged 
organ, with its lateral cecal 
pouches, may rupture, or the 
integument of the segment 
itself may give way, permit- 
ting the eggs to escape directly 
into the intestinal contents. 
As a rule these terminal or 
"ripe" segments are passed 
to the outside of the body of 
the host with the feces where, 
by their disintegration, the 
eggs are set free. 

The eggs of cestodes are 
globular or more or less oval 
in shape and are provided with shells of variable thickness (Figs. 96 
and 110). Beneath the shell is a translucent yolk which surroimds an 
inner covering containing the onchosphere (hexacanth) or six-hooked 
embryo (Fig. 112, a). In some forms the eggs as found in the feces 
•often have the outer shell absent. 

Life History. — Species of Tseniidse in which the development is 
known undergo a complex series of metamorphic changes, invoh'ing 
larval and sexually mature parasitism in hosts of differing species. 
After the egg, either free or vnth the segment entire, has been ingested 
by a proper larval host, the shell and embryonic envelope are digested 
away bj^ the gastric juices, and the onchosphere is freed (Fig. 112, a). 
At this stage the embryo is provided with three pairs of booklets by 
which it penetrates the intestinal wall and, probably- Ida- blood and 
l>iuph currents, may be carried to certain parts of the body specificalh" 
es.sential to its further development. Thus passively lodged, it loses 



P'iG. 9U. — .Segment of Tmiiia saginata, with 
sexual organs matured. Ovaries in lower portion 
to right and left; j-olk gland in extreme lower 
portion; shell gland between yolk gland and ova- 
ries; uterus, tubular organ extending upward; 
vagina, extending from glands to genital pore at 
left margin; testis, bodies distributed throughout 
segment-, vas deferens, convoluted organ extend- 
ing laterally to genital pore. Excretory vessel 
united by transverse commisures. Lateral longi- 
tudinal nerves shown by heavy lines. 



172 PARASITES OF THE DOMESTIC ANIMALS 

its hooklets and commonly' becomes surrounded by a capsule formed by 
proliferation of the connective tissue of the host, though this does not 
occur in all of the larval forms. 

At this stage the larva, which is now a mere vesicle containing more 
or less fluid and as yet without a head, is referred to as the acephalocyst 
(bladder-cyst), from which there may, in certain forms (echinococcus), 
develop multiple daughter cysts (Fig. 117). By a process of budding 
from the germinal wall, the acephalocyst now develops a further stage, — 
the cephalocyst (proscolex. Fig. 1 12, b and c), containing one (cysticercus, 
Fig. 107) or more (coenurus, Fig. 114) heads which conform with the 
scolex of the adult worm except that the larval head is invaginated. 

If the larva while still living at this stage is conve.yed to the digestive 
canal of a suitable host for the adult worm, the head is evaginated from 
the vesicle (Fig. 112, c), becomes detached from it, and, passing to the 
intestine, fixes upon the nmcosa by means of its suckers, to which attach- 
ment the crown of hooks contributes if this is present. By a process of 
budding, the scolex now jiroliferates a series of segments, each to be- 
come bisexually complete (Fig. 90). 

Sexual maturity of the segments marks the stage of the adult worm 
which, with its entire series, constitutes the chain, or, as it has been 
called by most writers, the strobila, a term which, with that of proglottid 
for segment, is discarded in this work. 

Tabular Review of Life History of T.tinia Saginata 
Adult Tapeworm in intestine of man 

i 
Egg. — Expelled from intestine. 

Hexacanth. — Freed from egg in digestive tract when 

I ingested by ox. 

Acephalocyst. — In striated muscle of ox. 

Cephalocyst (Cvsticercus). — Same. 

1 
Scolex. — Attached to mucosa of intestine of man 

I after ingestion of cejjhalocyst. 

Adult Tapeworm in intestine of man. 

Parasitism. — The tapeworms afford an example of extreme para- 
sitism. So far as known, their existence is wholly dependent upon 
alternate cystic and adult hosts, their development exhibiting no free- 
living stage. So afh-anced is their degeneracj' that there is little of 
organization remaining excepting the procreative, and this has acquired 



PLATYHELMINTHES 173 

a hyperdevelopment adaptive to the hazards encountered in the worm's 
life history. 

The classification of the tapeworms has been somewhat more artificial 
than systematic in that it has not sufficiently taken into account mode 
of development, a factor which should furnish the basis for their true 
natural affinities. Their larvse may, with reference to method of develop- 
ment, be placed in the five following forms: 1. Cysticercus (Fig. 107); 
2. ca^nurus (Fig. 114); 3. echinococcus (Fig. 117); 4. cysticercoid (Fig. 
96); 5. Tplerocercoid (Fig. 112,-e). The first three are found in organs 
or serous cavities of Herbivora and Omnivora, occasionally in Carnivora; 
the fourth fives mostly in invertebrates, and the fifth in the musculature 
of fishes. The more recent tendency in cestode nomenclature is to con- 
fine the generic name Taenia to those tapeworms which have a cysticercus 
stage in their life history. 

The cj^stic forms eniunerated above, with the conditions wliich cer- 
tain of them produce in their hosts, are taken up further on in the con- 
sideration of the cestode larvae. 

The accompanying tabular arrangement of the principal tapeworms 
considered in this work, with their adult and cystic hosts, is inserted 
for convenient reference. 



CHAPTER XV 
T.ENIASIS 

As to the effect of tapeworms upon their hosts, it may be said in gen- 
eral that serious disturliances are most hkely to be manifest when the 
worms are numerous, in which case the morljid effect is brought about 
by the operation of several factors. There may be a reduction or com- 
plete occlusion of the intestinal lumen with the usual inflammatory and 
toxic disturbances or displacements following interruption in the move- 
ment of the intestine's contents. While, as a general statement, in- 
vasion of the bile duct liy tapeworms may be said to be rare, the fringed 
tapeworm of sheep iThysanosomn actinioide-^) frequently enters this 
organ and therefore constitutes a more serious taeniasis in these animals 
than that from the Moniezia species. Armed tapeworms, by the irrita- 
tion from their hooks, will, essentially, set up an inflannnation of the 
mucosa iiroportionate to their number. Further, where the worms are 
numerous, their appropriation of nourishment contributes to the mal- 
initrition of a catarrhal enteritis. In heavy infestations the toxins 
elaborated by the worms imdoubtedly play a considerable part in the 
general systemic effect. 

The cystic forms of certain tapeworms have an important bearing 
upon the sanitary control of meat food jiroducts. In our own country 
this is esp(>cially true of the cysticerci of the two tapeworms of man, — 
Tcenia mginata and T. solium, the cysts of the former being harbored 
in beef, those of the latter in pork. The presence of these cysts in the 
muscles or other i^arts of the body constitutes the disease known as 
measles, to which affection the terms "measly beef" and "measly pork" 
have refei'enc^e. While observed most frequently in the animals men- 
tioned, measles may appear in sheep (Cysticercus tenuicollis, C. ovis), 
and man is occasionally auto-infected by larvae {Cysticercus celluloscB) 
of T(rnin soliian which he harbors. 

Cestodes of the Horse 

Three species of tapeworms occur in the Equidae. In all the cephalic 
armature and neck are ab.sent, and all have a genital pore on the same 
side in each segment. Nothing is known of their larval forms. 

1. Anoplocephala perfoliata (Taenia perfoliata). Fig. 91. Tseniidse 
(p. 170). — The head is large, rounded, and provided with well-developed 



Adult 


Hosts 


Armature 


hfVA 


Anoplocephala perfoliata 


Horse and ass 


Unarmed 




Anoplocephala mamil- 
lana 


Horse and ass 


Unarmed 




Anoplocephala plicata 


Horse and ass 


Unarmed 


' 


Moniezia expansa 


Cattle, sheep and 
goats 


Unarmed 




Moniezia alba 


Cattle, sheep and 
goats 


Unarmed 




Moniezia planissima 


Cattle, sheep and 
goats 


Unarmed 




Thysanosoma actinioides 


Sheep 


Unarmed 




Dipylidium caninum 


Dog, cat, man 


Armed 


Cryptocyss 
dectes 


Taenia hydatigena 


Dog 


Armed 


Cysticerci te 


Tipnia pisiformis 


Dog 


Armed 


Cysticercipii 


Multiccps multiceps 


Dog 


Armed 


Multiceps (u. 


Multiccps serialis 


Dog 


Armed 


Multiceps !ri 


Multiceps gaigeri 


Dog 


Armed 


Multiceps lis 


Echinococcus granulosus 


Dog, cat 


Armed 


Echinocccis 
losus 


Ta;nia tffiniajformis 


Cat 


Armed 


Cysticerci fai 


Cittota>nia <lenticulata 


Rabbit 


Unarmed 




Choanoticnia infundibu- 
lil'onnis 


Chicken 


Armed 


A Cystica' w 


Hymenolepis carioca 


Chicken 


Armed 




Davainea tetragona 


Chicken 


Armed 




Davainea cesticillus 


Chicken 


Armed 




Davainea echinobothrida 


Chicken 


Armed 




Davainea proglottina 


Chicken 


Armed 


A Cystice m( 


IVnia saginata 


Man 


Unarmed 


Cysticerci be 


Taenia solium 


Man 


Armed 


Cysticerci ct 


Diphyllobothrium latum 


Dog, cat, man 


Unarmed 


A plerocei )ic 











Hosts 


Parts Infested by Larva 


rho- 






























Flea, louse 


Body-cavity 


IDllis 


Ruminants and hogs 


Peritoneum 


f( nis 


Rabbit 


Mesentery and omentum 


OS 


Herbivora 


Central nervous system 


IJ: 


Rabbit and other ro- 
dents 


Connective tissue 


r 


Ruminants 


Central nervous system and 
connective tissue 


pu- 
kris 

\s\ 

ul'T 


Ruminants and hog 


Liver and lungs 


Rat and mouse 


Liver 






House fly 
















V 




Snail 




Ox 


Connective tissue of muscles 


Hog and other animals 


Connective tissue of muscles 


Fish 


Muscles 



TiENIASIS 



175 



suckers; it is prolonged behind by rounded flaps on the upper and lower 
side. The segments are very short, but wide, the width increasing 
toward the middle of the length of the body. 

Length, 2.5-3 cm. (1 inch); width, 3-15 mm. (1/8-5/8 of an inch). 

The eggs, by mutual pressure, are polygonal. The shell, as in other 
Anoplocephalinse, is prolonged by a pyriform point. They are 70-80 
microns in length. 

It lives in the small intestine and cecum, more rarely in the colon. 

2. Anoplocephala mamillana (Taenia mamillana). Fig. 91. 
Tisniidse (p. 170). — The head is small, somewhat angular, and has a 
central lineal depression from before to 
behind. It is provided with oval suckers 
located upon the side. The segments are 
nuich wider than long, progressively in- 
creasing in width from the head. Their 
length increases toward the posterior ex- 
tremity, the last segments being about 
half as long as broad. 

Length, 1-5 cm. (3/8-2 inches); width, 
4-6 mm. (J^ of an inch). 

The eggs are elongated and about 88 
microns in length. 

It infests the small intestine. 

3. Anoplocephala plicata (Taenia 
plicata). Fig. 91. Tseniida; (p. 170).— 
The head is rather large, broader than 
long, slightly concaved in the center. 
The four suckers are strong and are di- 
rected forward. The segments progres- 
sively increase in breadth and length to 
the posterior extremity. 

Length, 8-12 cm. (3 1/8-4 % inches); 
width, 8-20 mm. (5/16-% of an inch). 

The eggs are polygonal or round and 50-60 microns in length. 

It lives in the small intestine and has been foimd in the stomach. 

Occurrence. — Horses rarely harbor tapeworms. They are said to 
be most often found in the horses of Russia and to some extent m 
Germany and other European countries. The most common species is 
Anoplocephala perfoliata, while of the other two mentioned, Anoplo- 
cephala plicata is the more rare. 

Symptoms. — The presence of tapeworms in the intestines of the 
horse is seldom accompanied by perceivable symptoms. Those general 
to intestinal helminthiasis, as chronic digestive disturbances, with per- 
haps anseniia and general unthrift, may accompany the infestation 



Fig. 91. — Tapeworms of the horse. 
Left to right: Anoplocephala mamil- 
lana, A. perfoliata, A. plicata, nat- 
ural size. 



176 



PARASITES OF THE DOMESTIC ANI]\LALS 



tliough it can only be assumed that these symptoms are caused Ij.y tape- 
worms, even though the presence of the worms is made certain by the 
voiding of the segments. 



Cestodes of Cattle, Sheep, and Goats 

Cattle harbor three species of tapeworms. In all the heads are un- 
armed. Their larval forms are unknown. 

The three species of tapeworms of cattle also occur in sheep and 
goats. 

1. Moniezia expansa (Taenia expansa). Fig. 92. Tseniidse (p. 170). 
The head is small, generally pear-shaped. The 
suckers are slightly salient and slit-like. The an- 
terior part of the chain is filiform. The first seg- 
ments are very short, those which follow becoming 
longer, but always much broader than long. The 
broadest segments may reach a breadth of 2 cm. 
(■^4 of an inch). The genital pores are double 
and located on the lateral margins of the seg- 
ments. 

The lengtli vaiies considerably; it may be 15-30 
feet or more. 

The eggs are globular or polygonal and are 50-90 
microns in diameter. 

2. Moniezia alba (Taenia alba). Tteniidte (p. 170). 
— The head is larger than that of the preceding 
species and is pro\'ided with large oval suckers. 
The neck is short and the segments are longer and 
narrower than in M. expansa; some may be slightly- 
longer than broad. The width of the broadest 
segments is about 1 cm. (3/8 of an inch). There 
are two genital pores in each segnient. 
Its maximum length is about eight feet. 
The eggs are cuboidal and 48-58 microns in breadth. 
3. Moniezia planissima. TiBniidse (p. 170). — The head is nearly 
square and has slightly elongated suckers. The segments are much 
broader than long, the ripe ones having a width of 12-26 mm. (J^-1 
inch). These segments are very thin and semitransparent. Each seg- 
ment has two genital pores. 
Length, 3-6 feet. 

The eggs are about 63 microns in diameter. 

Thysanosoma actinioides (Taenia fimbriata). Tteniidse (p 170.). — 
This is a species occurring in sheep, but has not been reported in other 
domesticated Herbivora. The head is without hooks or rostellum. The 




Fig. 92. — Moniezia 
expansa, portions of 
adult, reduced (after 
Railliet). 



1 




T^NIASIS 177 

segments are broader than long, having the uterus transverse and the 
genital pores double or irregularly alternate. The segments have long 
fringes on their posterior borders (Fig. 93). 

Length, six inches or more. 

Its larval form is unknown. 

Occurrence and Symptoms. — All of these worms live in the small 
intestine. As nothing is yet known of their cystic forms, the mode of 
infection remains undetermined. Cattle are rarelj' disturbed in health 
by the presence of tapeworms. In exceptional cases there maj' be 
malnutrition and digestive disturbances accompanied bj^ bloating. 
Again, it is difficult to with certainty assign these nonspecific condi- 
tions to the presence of tapeworms. As in all mtestinal helminthiases, 
there is to be borne in mind the possibility of the worms passing to 
imusual locations, as the bile ducts, and of 
interference with the movement of the in- 
testinal contents by massed worms. 

Of the domesticated herbivorous animals, 
probably sheep most frequently harbor tape- 
worms. A species often found in those of 
the United States is Thysanosoma actinioides 
which, as is true of other species infesting 

sheep, is most prevalent among the flocks of Fig. 93.— Thysanosoma ac- 

the Western States. The worms mav be tinioides, anterior segments,— 

r , , , . J. ,, J.T, i_ ' enlarged (after Railliet). 

found at any tmie of the year, though more 

often during the season of grazing, a fact pointing to the probabilitj- 
that the encysted larvse are taken up with the grass. Thysanosoma 
actinioides, when brought to certain parts of the Eastern United States, 
does not multiply. It may be assumed that this is attributable to 
absence of the proper intermediate host, whatever that may be. In 
parts of the west it constitutes a form of tseniasis much more severe than 
that from IVIoniezia. This is due mainly to their invasion of the bile 
duct, a habit which is exceptional with other tapeworms, but with the 
fringed tapeworm it is the rule rather than the exception. 

Lambs born in the winter and turned upon grass during the rains 
and moisture of spring are the more likeh' to suffer from tapeworm 
invasion. In such cases, or in hea\^" infestation, anaemia is mdicated 
by paleness ^ of the visible mucosae, and this may be accompanied by 
loss of vivacitj^ and more or less emaciation with arrest in development. 
Straining and ineffectual efforts at defecation, with prolonged ele^■ation 
of the tail, are noticed, the feces later becoming unformed or even fluid 
and containing the segments. 

Death may ensue in advanced emaciation and weakness, or before 
reaching this stage if the intestine becomes obstructed by the worms 
in mass or there are other resulting complications. Such a course is 



178 PARASITES OF THE DOMESTIC ANIMALS 

rare in aged sheep. Where fataUties occur, they are usuallj' among the 
grazing hmibs. 

Cestodes of the Dog 

Of the tapeworms of the dog, nine are considered here, among which 
there is a wide variation as to frequency and importance. The fir.st 
eight of the species to be mentioned belong with the family TseniidiE; 
the ninth is referred to untler the Diphyllobothriidse. In all but the 
last the head is provided with the crown of hooks, and in all the life 
history is known. 

1. Dipylidium caninum (Taenia cucumerina). Fig. 9-4. Tseniidse 
(p. 170). — The head is small and has a protractile rostellum surrounded 
by the four suckers (Fig. 95). There are three to four rows of small 
thorn-like hooks. The neck is slender, succeeded at first by narrow 
trapezoidal segments. The nature .segments are longer than wide and 
shaped somewhat like a cucumber seed. They have a genital pore on 
each lateral mai'gin. 

Length, 15-40 cm. (6-16 inches). 

Eggs globular, 43-50 microns in diameter and grouped in small cap- 
sules (Fig. 96). 

The larva of this worm is a cysticercoid (Cryptocystis trichodedes) 
foimd in the body-cavity of the biting louse of the dog, — Trichodedes 
iatux (Fig. 96). Lice are not sufficiently prevalent upon dogs, however, 
to account for the fnniuent occurrence of this worm; in fact, later in- 
vestigations have determined that the dog flea, Ctenocephalus canis, 
and the human flea, Pidex irritans, harbor its larva, and it is probable 
tiiat the flea is its more conunon host. 

2. Dipylidium sexcoronatum. Ta>niida' (p. 170). — Hall and Wigdor 
(Journal of the American N'eterinary Medical Association, June, 1918) 
refer to this tapeworm as follows: "Dipylidium sexcoronatum has been 
reported from tlogs in the LTnited States at Bethesda, Md., and Detroit, 
Mich., by Hall (1917). We find it fairly often here at Detroit and our 
impression is that it is as common here as D. caninum. The strobila is 
nuich narrower than D. caninum. Some of the specimens with a narrow 
strobila appear to have only five rows of hooks and .should be studied 
with a view to determining whether D. sexcoronatum has sometimes five 
rows of hooks, as well as six rows, or whether this material belongs to a 
new species." 

3. Taenia hydatigena (T. marginata). Fig. 97. Taeniidi? (p. 170). — 
The head is small, but Utile broader than the neck. The hooks are 
large, 170-220 microns long, and number 30-34. The mature .segments 
are wider than long, the distal segments elongated. The gravid seg-. 
ments have a median longitudinal groove terminating in a notch pos- 



TiENIASIS 179 

teriorly. The number of segments is about 400. The gravid uterus has 
5-10 branches on each side. 

Length, 1.5-2 meters (57-76 inches). 

Eggs nearly spherical and 31-36 microns in diameter. 

The larva is a cysticercus (Csyticercus tenuicollis) found in the per- 
itoneum and, more rarel3', in the pleura of iiuninants and hogs. It has 
also been reported from rodents and monkeys. 

4. Taenia pisiformis (T. serrata). Fig. 98. Tseniidse (p. 170). — 
The head is small, but little broader than the neck. The hooks are 
large, 225-294 microns long and 34-38 in number. The segments are 
at first narrow and much shorter than broad ; those mature are appro.x- 
imately square. The distal segments are elongated (10-15 mm. by 
4-6 mm.). The posterior margins of the segments project laterally, 
giving to the lateral margins of the chain a serrated appearance. The 
genital pores are prominent, and the uterus in gravid segments has 8-14 
lateral branches on each side. 

Length, 0.5-2 meters (19-76 inches). 

Eggs oval, 36-40 microns long, 31-36 microns wide. 

The larva is a cysticercus {Cysticercus pisiformis) which develops in 
the mesentery and omentum of rabbits, and has been found in the mouse 
and beaver. 

5. Multiceps multiceps (Taenia ccenurus). Fig. 113. Tseniidae 
(p. 170). — The head is small and bears 22-30 hooks. Larger hooks have 
a handle equal in length to that of the blade and wa-\^' in outline. The 
segments of the middle portion of the chain are appro.ximately square. 
The distal segments are elongated (8-12 mm. long by 3-4 mm. wide). 
The ripe segments are broader at their middle, narrowing toward their 
ends which gives them somewhat the appearance of a cucumber seed. 
The genital organs are well developed, 15-20 cm. (6-8 inches) from the 
head, or toward the 125th segment. The genital pores are irregularlj^ 
alternate. The uterus has 16-25 lateral branches on each side. 

Length, 40-60 cm. (16-23^ inches). 

Eggs nearly spherical and 31-36 microns in diameter. 

The larva is a ccenurus (Multiceps multiceps; Ccenurus cerehralis) 
which develops in the cerebral cavity and, more rarely, in the spinal 
canal of herbivora, usuall.y sheep (Figs. 114 and 116). 

6. Multiceps serialis (Taenia serialis). — Tseniidie (p. 170). The 
head is a little wider than the neck and bears 26-32 hooks. The small 
hooks have a short blunt handle; the larger hooks a wslyj handle as 
long or a little longer than the blade. The segments are similar to those 
of M. multiceps, the foi-m of the uterus in gravid segments also being the 
same. 

Length, 44-74 cm. (17-29V2 inches). 

Eggs oval, 34 microns long, 27 microns wide. 






Fig. 96. — Egg packet of Dipylidium 
cauinum (left); Cysticercoid (rigfit). 



Fig. 95. — Head of 
Dipylidium caninum. 
with rostellum pro- 
jected. 



Fig. 94. — Dipyli- 
dium caninum, por- 
tions of adult, — 
natural size. 





Fig. 9S. — Tsenia pisiformis, 
portions of adult, — natural size. 



Fig. 97. — Tcenia hydati- 
gcna, portions of adult. — nat- 
ural size. 



Fig. 99.— 
Echinococcus 
granulosus, — 
enlarged (af- 
ter Boas, by 
Kirkaldy and 
Pollard). 



TiENIASIS 181 

The larva is a coenurus {Multiceps serialis; Coenurus serialis) found 
in the connective tissue of rabbits and other rodents. 

7. Multiceps gaigeri. Taeniidee (p. 170). — This is a species found 
in India and Ceylon, and described by Hall (Journal of the American 
Veterinary Medical Association, November, 1916), the larva of which 
develops in the central nervous system and also in the connective tissues 
and serous surfaces of ruminants. Thus in its cystic host this species 
combines the location of M. rnuUiceps and M. serialis, the larva, as in 
that of the latter, forming an adventitious capsule. 

The material for examination (Bureau of Animal Industry, Hel- 
minthological Collection) consisted of specimens of tapeworms from 
the dog and the coenurus from the goat. From his study of these, Hall 
(1916) regards this species as more closely related to the gid tapeworm, 
M. multiceps, than to M. serialis. 

8. Echinococcus granulosus (Taenia echinococcus). Fig. 99. 
Tseniidaj (p. 170).— The chain is but 4-6 mm. (3/16-1/4 of an inch) in 
length, and is composed of a head and three segments. The head is 
provided with 28-50 small hooks arranged in two rows. The first and 
second segments from the scolex are incompletely developed, but one 
segment at a time becoming gravid, — the third, when its length ahiiost 
reaches that of the rest of the worm. 

Eggs oval, 32-36 microns long, 25-26 microns broad. 

The larva is an echinococcus {Echinococcus granulosus; E. polymor- 
phus) found in the internal organs, usually the liver and limgs, of rumi- 
nants and hogs, and also in man (Fig. 117). 

Occurrence. — It follows from their habits that dogs should more 
frequently harbor intestinal parasites than other domestic animals. 
Probably over fifty per cent, are infested with varied species, frequently 
in considerable number. Of these, tapeworms predominate, several 
species of which often inhabit the intestine of a single individual. 

The intermediate hosts of Dipylidium caninum — fleas and lice, the 
former ubiquitous in relation to canine existence, — would account for 
the greater frequency of this tapeworm than any other in dogs. Dogs 
which have access to butchers' offal are, in addition to this species, 
readily infected with Echinococcus granulosus, Tcenia hydatigena, and 
Multiceps multiceps, the cystic forms of which are harbored in organs 
of the principal meat-food animals, sheep, hogs, and cattle. Huntmg 
dogs and those which roam afield are the most exposed to invasion with 
Tcenia pisiformis and Midticeps serialis, these having their larval de^'el- 
opment in rabbits. In any case, young dogs are more susceptible to 
intestinal helminthiasis than those which are older. 

Symptoms. — Notwithstanding their frequent presence in large num- 
bers, tapeworms seem, as a rule, to have little deleterious influence 
upon the health of dogs. As is true of intestinal worms ui general, 



182 PARASITES OF THE DOJUESTIC ANIMALS 

their accumulation may bring al)Out obstruction with attendant dis- 
placement and degenerative changes in the intestinal walls; and, again, 
there may be a serious and even fatal result from their unusual location. 
Such conseciuences of tffiniasis are, however, exceptional in dogs. In 
genei'al, the s^nnptoms are those of chronic gastro-intestinal catarrh. 
The capricious appetite varies between extreme voraciousness and com- 
plete anorexia. Regardless of the amount of food consumed, there is a 
noticeable emaciation which may become well marked, young dogs 
especially becoming pot-bellied and stunted in growth. More char- 
acteristic is restlessness, straining, and itching about the anus, the latter 
manifested by agitation of the tail and a peculiar squatting and dragging 
of the hind parts, sometimes referred to in the expressive, l)ut highly 
untechnical term, "rough-locking." 

With increasing luieasiness, the development of intestinal pains, 
howling, and an inclination to bite, which is perhaps conjoined with a 
dull or wild expression, there are presented STOiptoms somewhat similar 
to those of rabies. In such cases convulsions may set in and the animal 
may die during an attack, or it may gradually succinnb after sinking 
into a cataleptic condition. 

Pathogenesis. — Necropsies upon dogs which have suffered from 
t;pniasis generally show the worms lodged in the small intestine only. 
Probably as a result of post-mortem wandering, they may also be found 
in small numbers in the large intestine or stomach. The inflannnation of 
the nnicosa is especially extensive and of aggravated character in in- 
festation with Echinococcus. This is a tapeworm of the dog which, 
though relatively very small, sets up the greatest irritation by reason 
of the vast number of individuals present, which, firmly implanted by 
their hooks, may completely cover the intestinal lining over large areas. 
Where obstruction occurs in taeniasis, it is generally brought about by 
the presence of the largei- tapeworms massed in coils. Dipylidium 
caninum, though smaller than some other species inhabiting the dog, is 
most likely to be found the offending agent in such conditions because 
of its prevalence and the presence of numerous individuals in the 
same host. The projecting rostellum of this species, sinking deep 
into the mucosa, is also a factor increasing its capabilities for dam- 
age. Tasnia hydatigena and T. pisifonnis are much larger, but less 
common, while MuUiceps midticepi^ and M. serialis have thus far 
heen found more connnonly in European countries than in the 
United States. 

Contrii)uting to the systemic effects of tapeworm invasion, there is, 
as in other helminthiases, the operation of toxins elaborated by the 
worms. In cases of heavv' infestation this factor must be a considerable 
one, especially when combined with that of jioisons derived from the 
dead and decomposing bodies of the parasites. 



T^NIASIS 183 

Diagnosis. — The presence of tapeworms may in most cases be recog- 
nized by the passing of segments, or fragments of the chain, with the 
feces; occasionally these may also be expelled with vomited matter. 
Often the fragments may be arrested near or partly protrude from the 
anus, causing a pruritus in this region which the animal endeavors to 
relieve by rubbing the parts upon the ground. 

•Diagnosis may be assisted in doubtful cases by the administration 
of a laxative, in the operation of which detached portions of the chain 
will be expelled if present. Echinococcus, however, on account of its 
suTall size, is likely to escape observation in the ordinarv means of 
examining fecal matter. 

Dog Tapeworms in Relation to Human Infection. — Two species of 
tapeworms harbored by dogs — Echinoccocus granulosus and Dipylidium 
caninum — are especially of medical interest in that the}'' may also 
infect man. The first mentioned produces in its larval development a 
condition known as hydatid disease, or echinococcosis, in man as well 
as in numerous lower animals. 

The larval or, as it is called, the hydatid form of this tapeworm occurs 
usually in the liver, lungs and kidnej's of these animals, and may pro- 
duce from the original cyst numerous daughter cysts, the growth going 
on indefinitely and evolving bladders as large or even much larger than 
an orange (Fig. 117). Due to its pressure, necrotic degeneration of 
tissue, and also to secondary infection by bacteria, this growth gives 
rise to serious disturbances in the organ in which it is lodged. In man 
the condition is often fatal, less so in the lower animals, probably owing 
to the fact that their term of life is shorter, or they are likely to be 
slaughtered before sufficient time has elapsed for the full development 
of the slow-growing hydatid. 

A more detailed reference to the echinococcus c.yst is given further 
on in the special consideration of the cestode larva (p. 210). , 

The common tapeworm of the dog, Drpylidium camnuin, may find 
adult hostage in the human intestine. According to Hall (Bull. 260, 
U. S. Dept. of Agriculture, 191.5), seventy-six cases of this tapeworm 
in man, mostly children, have been reported, a number of these from 
the United States. It has been found in an adult thirty-eight years old, 
and it is stated that as many as two hundred and fifty-eight of these 
worms have been found in a single person. 

Considering the privileges which are allowed dogs, it is quite apparent 
that a flea or louse containmg the Crj-ptocystis might pass from the dog 
to the human mouth by the dog licking the face, or through the inter- 
nuHliation of food, especially sticky candy to which the insect readily 
adheres. Children give little attention to incidental contamination 
of their food, which is frequently partaken of in intimate proximity to 
their canine companions, the dog often sharing in the feast — perhaps 



184 PARASITES OF THE DOMESTIC ANIMALS 

from the same plate. It follows that human infection with this tape- 
worm occurs more often among children than among adults. 

As in tceniasis of other animals, the presence of a few of these worms in 
man is not likely to occasion serious disturbance, though to the hmiian 
conception, the presence of a tapeworm in the intestine is anything 
Ijut a pleasant thing to contemplate. Where they are numerous, the 
irritation, possible obstruction, and other secondary complications which 
may arise, make it, as in lower animals, a more serious condition. 

Prevention calls for restraint in the liberties of dogs, especially about 
children. Children should not be permitted to handle vagrant and 
neglected dogs. Those kept about the premises as pets should be ob- 
served for indications of the presence of tapeworms, and their bodies 
should be kept free from fleas and lice. 

Cestodes of the Cat 

Of the tapeworms harbored by cats, only the species Tasnia tcenice- 
formis is of importance as affecting their health. Others which have 
bet'ii found aie; Dipyliclhim caninum, Echinococcus granulosus, and 
DlphyUobothriinn latum, the first two described under 
the Tteniidse of the dog. These latter forms do not 
appear to cause disturbance to the animal. 

Taenia taeniaeformis (T. crassicollis). Taeniidae 
(p. 170). — The head (Fig. 100) is rounded, has four 
prominent suckers and a strong rostellum pro\'ided 
with 26-52 hooks. The neck is as wide as, or wider 
than, the head, and there is no intermediate constric- 
I'lo. 1110— Head of tion. The segments follow immediately from the head, 
Tipiiia ta^nicBformis, increasing in size to a length of 8-10 mm. (5/16-3/8 

Length, 15-60 cm. (6-23J/2 inches). 

Eggs globular, 31-37 mici'ons in diameter. 

The larva is a cysticercus {Cysticercus fasciolaris) inhabiting the 
liver of rats and mice. 

Occurrence and Symptoms. — This tapeworm is not uncommon 
in the cat, often infesting the small intestine in large numbers and 
seriously affecting the animal. 

There is in the beginning a diminution of appetite which gradually 
passes to refusal to take any food whatever. Diarrhea, at first slight, 
later severe, is succeeded by constipation; there is salivation, and in 
some cases vision and hearing are seriously affected. Colic is a frequent 
accompaniment during the attacks of which the animal may rush about 
in a frantic manner, apparently heedless of or unable to see objects with 
which it may come in contact. 




T.ENIASIS 185 

Finally, as a manifestation of the nervous disturbance, there are 
convulsions; there is much prostation and emaciation, and the animal 
dies, usually durmg or shortly after an epileptiform attack. 

Cestodes of Rabbits 

Tapeworm mfection is said to frequently appear enzootically among 
the wild hares of foreign countries. In domestic rabbits such infection 
is rare. The species here described is occasionally found. It is unarmed, 
and its life history is unknown. 

Cittotsenia denticulata (Moniezia denticulata). Taeniidffi (p. 170). — 
The head is small, with flat suckers. The neck is as broad as the head. 
The larger segments may be 10 mm. (3/8 of an inch) in width, alwaj^s 
wider than long. The genital pores are on the posterior fourth of the 
border of the segment. 

It may reach a length of 8 cm. (3 inches). 

There is Httle clinical experience with tseniasis of rabbits. In general, 
what has been said as to such infection in other animals will apply as 
well to them. Diagnosis can be made by finding the segments in the 
feces, or by destrojang and examining one or two suspected animals. 

Family II. Diphyllobothriid.e 

The best known representative of this family is Diphyllobothrium 
latum (Dibothriocephalus latus, Bothriocephalus latiis). The head is 
oblong or lanceolate, unarmed, and has two deep slit-like depressions, 
one dorsal, the other ventral, which serve as suckers (Fig. 109). The 
neck is not well demarcated from the first segments which are scarcely 
visible. The segments gradually increase in length and breadth; the 
largest are 4-5 mm. long and may be 2 cm. wide (3/16 by 3/4 of an 
inch). The gravid segments become much narrower as their genital 
organs atrophy and the eggs are- discharged, these being expelled in 
greater part before the separation of the segments from the chain. In 
sexually mature segments the rosette-shaped uterus maA' be seen in the 
middle line. The genital pores are special orifices for ovulation, located 
in the middle of the ventral surface of the segments (Fig. 101). 

The length of the entire worm may be 2-7 meters (6-22 feet). It 
may reach a length of 20 meters (Neumann). The segments may 
number 3,000 or more. 

The eggs are oval, operculated, and 68-70 microns long. In the 
presence of water a ciliated embryo escapes from the egg by the lifting 
of the operculum and swims about until it enters the body of a fresh- 
water fish, said to be especially the pike. In the muscles of this host it 
develops into the worm-like plerocercoid (Fig. 112, e). After the 



186 



PARASITES OF THE DOMESTIC ANIMALS 



definitive host has eaten fish containing the hving larvje, the tapeworms 
develop ra])idly, becoming mature in about four weeks. 

Occurrence. — This species is sometimes called the broad Russian 



r^SiStixSa t'2r.:^'-^-::=333::3kdkM§^U^^^Ssd 









iHiigSS 




Fio. 101. — Sections of niphylloljothiium latum. — natural size (after Boas, by Kirkaldy 
and Pollard, from LeuckartJ. 

tapeworm. It infests man and fish-eating dogs in Russia, Switzerland. 
Japan, Finland, Sweden, and other foreign countries. It is extremely 
rare in the United States, and is of little medical or economic importance 
here. 

Tre.\tmext of T.exiasis 

Treatment of Taeniasis of the Dog. — Therapeutic measures for the 
expulsion of tapeworms have two consecutive objects in view; first, the 
bringing about of a torpid condition or weakening of the worm; second, 
the expulsion of the entire worm from the host. The first is attained in 
part b.y depiiving the parasite of its nourishment, and by the adminis- 
tration of a vermifuge which should sufficiently further weaken it to 
cause its detachment from the mucosa; the second by a purgative which 
will expel the detached worm with the evacuations. 

As preparatory to the action of the vermifuge, all food should be kept 
from the animal for at least twenty-four hours immediately preceding 
its administration; at the same time the cleaning out process will be 
considerably aided if a mild laxative is given. Some advocate a milk 
diet for several days, but in any case the fasting should be absolute for 
a period of one day. 

Of the vermifuge agents, those which have been found most reliable 
as tseniafuges are: (1) male fern (aspidiuin); (2) areca nut; (3) kusso; 
(4) kamala. Of these male fern is particularly serviceable. Depending 
upon the weight and age of the animal, the oleoresin of aspidium may 
be given to dogs in doses of fifteen minims to one dram. It can be 
advantageously combined with small doses of areca nut (one grain per 
pound of body-weight), and conveniently administered in capsule. 
Aspidium should never be given with oil as this favors its ab.sorption, 
and it is a local action which is sought. After three to four hours the 



TiENIASIS 187 

dose may be repeated, and twelve hours after the first dose a purgative 
should be given. 

The dog should be kept where its evacuations can be conveniently 
examined, and, if it is found that the head of the tapeworm has not been 
expelled, the treatment is to be repeated in a week to ten days. The 
expulsion of the worm may be aided somewhat by rectal injections of 
warm soapy water. 

If areca nut is used uncombined, it may be given in closes of two 
grains for each pound of body-weight. It can be conveniently adminis- 
tered shaken up in a little milk. Areca nut in itself is laxative or purga- 
tive according to dosage. If purgation has not followed within a few 
hours after its administration, a full dose of castor oil should be given 
ten to twelve hours later. 

Kusso has an advantage in being quite safe even in excessive doses. 
Small dogs take of the fluid extract one-half to one dram; large dogs, 
two to four drams. It can be given in milk and repeated three times at 
intervals of one hour. Vomiting, which sometimes follows the adminis- 
tration of kusso, may be prevented by previously giving a medicament 
having an anesthetic action upon the stomach. 

Kamala is given to dogs in doses of one-half to two drams in honey or 
syrup. In cases where heavj^ infestation is suspected it should be re- 
peated in eight hours. Kamala has some purgative action and maj' 
also nauseate; the latter effect can be corrected bj^ the same means as for 
kusso. 

Other tiEuiafuges sometimes used are: (1) Pumpkin seeds, fed crushed 
and macerated or as an infusion, and (2) turpentine, one-half to one 
dram, given with the yolk of an egg and repeated imtil three doses- have 
been administered twenty-four hours apart. Turpentine, however, on 
account of its irritant effect upon the kidneys, should be used with 
caution. 

Whatever form of tseniafuge medication may be chosen, the chances 
of success will depend much upon a brisk purgative action following 
upon its operation. At best there is often failure to secure the head of 
the worm, in which event a repetition of the whole treatment is called 
for in the course of one to several weeks. 

Prevention. — To prevent the spread of tteniasis, all expelled tape- 
worms and, their fragments should be destroyed by burning. Dogs 
known to be infected had best be isolated and all of their excrement 
burned. Dogs which have their meat cooked, and those which are not 
allowed access to the viscera of slaughtered animals and rabbits, are 
not so likely to be infected, though such precautions will not protect 
them from the common species Dipylidium caninum, freedom from fleas 
and lice, and prevention from association with dogs less fortunate in 
this respect, being essential to avoidance of infection by this species. 



188 PARASITES OF THE DOMESTIC ANIMALS 

Treatment of Taeniasis of the Cat. — For taeniasis of the cat the same 
pi'ocedure may be followed and the same remedies used as for the dog. 
The dosage, however, should be reduced and proportioned according to 
the weight and age of the animal. 

Prevention consists in restraining the animals from feeding upon 
rats and mice, — the intermediate hosts of their most common tape- 
worm , — Tivn ia tcvn iajorm is. 

Treatment of Taeniasis of Sheep and Goats. — For several days pre- 
ceding treatment of these animals it is advisable to feed moderately 
upon green succulent food, avoiding bulk, as fodder and hay. Imme- 
diately before giving the vermifuge all food should be withheld for a 
sufficient time to make the animals quite hungry. Powdered areca nut 
may then be given in one to two dram doses according to weight. It 
can be administered mixed with bran or bran and chopped beets which 
the sheep, made ravenous by their preliminary fast, will eat greedily. 
Three horn's afterward a purgative should be given and the evacuations 
of each individual kept under observation for the appearance of tape- 
worms. 

Otlu'r vermifuges reconunended are: (1) Oil of turpentine, one to two 
drams, given in one-half to one ounce of linseed, cottonseed, or olive 
oil, and (2) kamala, forty-five grains to one and one-half drams in thin 
syruj) or water, the dose to be repeated once at an interval of four hours. 

Treatment of Taeniasis of Cattle. — Where treatment is indicated for 
the expulsion of lajieworms of cattle the animals should be dietetically 
jiiepared as recommended for sheep. As a vermifuge, tartar emetic is 
(juite suitable for these animals. It may be given in one and one-half to 
two and on(>-half dram doses in gruel. Oil of turpentine, three ounces 
in a pint of linseed oil, makes a reliable remedy. Arsenic in daily 
ascending do.ses for a i)eriotl of fifteen days has also been recommended. 
The vermifuge treatment should lie followed by a purgative of glauber 
salts. 

Treatment of Taeniasis of the Horse. — The existence of tapeworms 
in the horse generally remains mu-ecognized during life. The symptoms 
are those general to intestinal helminthiasis of horses, and the treat- 
ment is quite the same as that for ascariasis (p. 234). The animal is to 
be removed from work, kept from hay, and fed only upon mashes. After 
at least twenty-four hours of such preparation, give two to four ounces 
of oil of turpentine, and one dram of oleoresin of aspidium in a pint of 
linseed oil. Tartar emetic is also quite effectual. It should be given 
in two doses of three drams each at an interval of twelve hours. It 
may be mixed with a gi-uel of linseed meal. 



CHAPTER XVI 

TAPEWORMS OF CHICKENS 

Though tapeworms are comparatively frequent in chickens and other 
domestic fowl, they have not up to quite recent times been the subject 
of any considerable investigation in this countr3'. In our hterature upon 
the parasites in general, if not neglected entirely, but one or two species 
are as a rule described, and these generally in an incomplete manner. 

With the exception of but one species, .what is at present known as 
to the larval forms has been determined from studies upon poultry 
cestodes in foi'eign countries. Thus far in these investigations the hfe 
cycle of but one chicken tapeworm — Davainea progloUina — has been 
experimentally demonstrated, the only one among the six here described 
which has not been reported in this countr}^ The remaining five have 
been found infesting chickens in various parts of the United States. 

1. Choanotaenia infundibuliformis {Dre-panidotcenia infundi- 
hidiformis) (Fig. 102) — The head (Fig. 103) is small, globular 
or conical, and bears a crown of 16-20 hooks. The suckers 
are prominent, may be projecting. The neck is very short. 
The first segments are short ; those following are infundibuli- 
form, with anterior border narrower than the posterior. The 
genital pores are irregularty alternate. 

The length varies from 2-23 cm. (^-93^ inches). 

Grassi and Rovelli, comparing cysticercoids which they had 
found in flies (Musca domestica) with the adult Choanotccnia 
infundibuliformis, noted a structural agreement from which 
they inferred that the larvae were the intermediate stage of 
tliis species. No experiinents were carried on by these in- 
vestigators, however, to demonstrate this connection. 

Guberlet, of Oldahoma Agricultural and Mechanical Col- 
lege, in a series of investigations upon chicken cestodes (1912- Fig. 102. 
1914) seems to have conclusively demonstrated that the "^9'^°'^"°" 

... . , tsema in- 

cysticercoid of Choanotcenia infundibidiformis occurs m the fundibuU- 
common house fly. Briefly stated, his results were obtained formis, — 
by raising cysticercoids in the flies by feeding them on the "'^ " ^'^^' 
eggs of the tapeworm. These flies were fed to three of six chicks 
which had been removed from chance infection as soon as hatched. 
Three weeks after such feeding all of the chicks were killed, and two were 
found to be infested with Choanotcenia infundibuliformis. The three 
birds used as a check on the experiment contained no worn^s. 



190 



PARASITES OF THE DOMESTIC ANIMALS 



2. Hymenolepis carioca. — The head is piriform with retractile 
rostelhmi. It is iinanned. The segments number about 500, all much 
wider than long; terminal segments measure 0.5-0.8 mm. The genital 
pores are unilateral. The worm is very fragile and delicate. 

Length, 3-8 cm. (1J4-3 1/8 inches). 
The life history is unknown. 

3. Davainea tetragona iTcenia tetragona). — The head (Fig. 104) is 
small and tetragonal; lostellum armed with a crown of 100 hooks. The 
suckers are oval and armed with 8-10 circlets of small booklets. The 
short neck is followed by short trapezoid segments, those terminal 




l'"io. 103. — Choano- 
ta!iiia iiifundibulifor- 
inis, srolpx miifli ron- 
t r a c t (• <1 , — enlarged 
(after Guberlet, in 
"Transactions of the 
American Microscopi- 
cal Society"). 



Fig. 104.— Scolex of 
Davainea tetragona, — 
enlarged (after Guber- 
let, in "Transactions 
of the -\merican Mi- 
croscopical Society".) 



Fig. 105. — Scolex of Da^•ainea 
echinobothrida, — enlarged (after 
Gnheiiet, in "Transactions of the 
-American Microscopical Society".) 



generally longer than wide. Their length varies between 1-4 mm. The 
genital pores are unilateral. 

The length vari(>s between 1-25 cm. (3/8-10 inches). 

Investigations of Piana point to certain little snails (Helix carthit- 
sianelld and //. iiiaciilosd) as the probable larval hosts of this species. • 

4. Davainea cesticillus (Tcenia cc.sticillus).— The head is globular 
and has a lostelluni scarcely salient or depressed. It is armed with a 
double crown of 400-500 booklets which are loosely attached. The 
.suckers are small and unarmed. There is no neck. The first segments 
are short and much wider than the head; the last are about as long as 
bi-oad. The genital pores are irregularly alternate. 

Length, 1-4.5 cm. (3/8-1 3/4 inches). By some authors it is said to 
att.-iiii a much greater length (10-13 cm.). 



TAPEWORMS OF CHICKENS 191 

According to Grassi and Rovelli the intermediate host is a lepidop- 
terous or coleopterous insect. 

5. Davainea echinobothrida {Tcenia echinobothrida). — The small 
head (Fig. 105) presents an infundibuimn provided with a double crown 
of about 200 hooks. The suckers are ai-med with 8-10 circlets. There 
is no neck. The segments gradually increase in width, the largest being 
1-4 mm. The genital pores are irregularlj- alternate. 

Length, 5-25 cm. (2-9J4 inches). " 

Nothing is known of its larval development. 

This species has a characteristic pathological effect in that the scolex, 
with its accessory armature about the suckers, bores through the in- 
testinal mucosa, producing large nodules or ulcers. The condition in 
fowls is termed "nodular tseniasis" and is described by Moore (Bureau 
of Animal Industry, Cir. No. 3, 1895). The nodules are often mistaken 
for other diseases showing similar features. 

6. Davainea proglottina (Tcenia proglottina) . — The head is quad- 
rangtilar, slightly rounded. The rostellum is armed at its base with 
80-95 hooks. The chain is composed of 2-5 segments. The terminal 
and largest segments have a tendency to detach and develop separately 
in the intestine. These free segments may acquire a length exceeding 
that of the entire chain. The genital pores are irregularly alternate. 

Length, 0.5-1.55 mm. 

Grassi and Rovelli have demonstrated that the larva of this species 
is a cysticercoid which inhabits several species of snail — Limax cinereus, 
L. agrestis, L. variegatus. 

The species has not as yet been reported in this country. 

Occurrence. — Guberlet, in a report of his investigations carried on 
in Nebraska (Journal of the American Veterinary Medical Association, 
Maj^ 1916), sets forth some significant data as to the prevalence, in 
parts of the LTnited States at least, of chicken cestode infection. During 
1912-13 he examined sixty-eight birds collected mostly from Nebraska 
and Illinois. From this material he obtained 1,561 tapeworms, specif- 
ically distributed as follows: Davainea tetragona, 598; D. cesticillus, 582; 
Choanotcenia infundibuliformis, 176; Hymenole'psis carioca, 154; Davainea 
echinobothrida, 51 . The worms were present in numbers per host varying 
from 1-35. (The author is informed by Dr. Guberlet that he has since 
found as many as 115 in a single animal.) Most of the birds examined 
ranged in age from four to six months. 

Symptoms. — As a rule it is only in moderate to heavy infection that 
tapeworms bring about morbid conditions in fowl. In any case the 
s\^nptoms are not well defined. They may vary in different individuals 
having an equal degree of infestation, age especially having an influence, 
young birds lieing much more affected than adults and exhibiting the 
.s.\nnptoms moi'e definitely. The following are among the more usual: 



192 PARASITES OF THE DOMESTIC ANIMALS 

There is an abnomial desire for food, in spite of which the heavily 
infested chickens emaciate and become anaemic, as manifested by pale- 
ness of the comb and wattles. The feathers become erect, ruffled, and 
dull, and the birds have a tendency to isolate themselves, often in 
drooping attitudes, or the constantl^y hungry creatures may seem never 
to be at ease, but are constantly running aljout, this probably accounting 
in part for the loss of flesh. In such aggravated cases there is often ad- 
vanced emaciation, and, completely exhausted, the bird may die. 

Diagnosis. — A reliable diagnosis can only be made by finding the 
segments in the feces, or by killing and examining one or two of the 
birds showing suspicious symptoms. When the latter method is adopted 
the intestine should lie removed and slit open under water. After 
gentle stirring to remove the contents, it may be transferred to a basin 
of clean water, when the worms, if present, will usually be seen attached 
to the nuicosa. 

Control. — As in other forms of helminthiasis, control measures are 
most effectually ajiplied to the jiarasites in their stage of larval develop- 
ment. Until more is known of the life histories of the chicken tapeworms 
little can be done in the waj^ of prevention other than that based by 
analogy upon what has already' been demonstrated. It is scarcely 
practical to keep poultry from eating .such possible intermediate hosts 
as worms and insects. Means may be taken, however, to restrict their 
access to flies, snails, and the lower crustaceans of stagnant water, 
though .such precaution cannot well be applied to birds running at large. 
A more feasible accessory measure is the prevention of the larvae from 
reaching the intermediate hosts by isolating the infected birds in screened 
quarters where their droppings maj^ be collected and made sterile by 
burning or other means. 

Treatment. — ^'ermifuges may be administered in the form of pills 
maiic up with bread. Probably the most suitable is a.reca nut which 
can bo given to adult chickens in doses of from ten to twenty grains 
according to weight. Young animals may take from three to five 
grains. After three daj's the treatment should be repeated. Other 
remedies used arc male fern, kamala, turpentine, and pumi:)kin seeds, 
the dosage being proportionate to weight. 

Such a inethofl of treatment has a disadvantage in that each bird 
must be treatefl individually. Where the infection occurs in large 
flocks the repeated handling of each birr! involves such an amount of 
time and patience as to put it practically out of the question. Again 
we are indebted to Gul)erlet for experiments which seem to point the 
way to a moi'e practical method. Bearing upon this department of his 
work, his report is here quoted in part. 

"Fifteen birds which showed symptoms of tapeworm infection were 
placed in a cage which was insect-proof and were given the following 



TAPEWORMS OF CHICKENS 193 

treatment : A gallon of a mixture of wheat and oats, to which was added 
a small tablespoonful of concentrated lye, was cooked slowly for about 
two hours and allowed to cool. The birds were fasted for about fifteen 
hours and were then given as much of the mixture as the}' would eat, 
with plenty of water. Twelve hours later one of the birds was killed 
and an examination of the small intestine was made. It was found 
that nearly all of the worms in the intestine were loose, the scolices being 
detached from the wall, and were also apparenth' dead. The rest of 
the birds were given a second dose twenty-four hours after the first. 
Many worms had passed with the droppings in from twenty-four to 
twenty-six hours after the first feeding. Most of the worms in these 
droppings were dead, but in all probability the embrj'os were still alive 
in the mature proglottids. Twelve hours after the second dose was 
given another bird was killed and it was found that onty a few worms 
were left and all of these were detached and dead. The intestine was 
filled with a peculiar graj'-colored, slimj^ substance composed mainh- 
of mucus. Many entire worms and fragments were passed with the 
droppings during the period of feeding. The lye acted to some extent 
as a purgative. 

"The birds were given normal diet again, and in a few days they 
showed no sjinptoms of infection. Eight days after the second dose had 
been given two more birds were killed and examinations made. One 
possessed a small fragment of a tapeworm and the other was entirely 
free. 

"This remedy has been known to many poultry raisers for some time, 
but they have neglected to use it, mainly on account of the fact that 
heretofore no definite evidence has ever been presented concerning its 
actual worldng possibilities. It may not, and in all probabilit.v will not, 
remove all of the worms, but it does remove most of them so that they 
are not serious and can be controlled in the flock as a whole." 



CHAPTER XMI 



THE TAPEWORM LARV.E 



Certain taj^eworms arc to be considered as to their pathogenicity 
from two important points of view. They are not only parasites in their 
adult state in the intestines of domestic carnivores and man, but, in^the 
larval stage live as somatic parasites in animals used as food by man 
and it may be in man himself. Depending much upon their numbers 
and form of cyst, these cause no disturbance to their host, or, through 
their growth, pressure, and inaccessibility, may constitute a menace to 
health far more serious than that of the adult worms in the intestines. 

Three forms of cestode larvse are principally concerned in this connec- 
tion, — cysticercus (Fig. 107), co-nurus (Fig. 114), and echinococcus 
(Fig. 117). A brief synoptical arrangement of these, including the 
cysticercoid and plerocercoid, follows: 

I. Larva having a caudal vesicle. Cystic 

A. I>arva of large size. Liquid in caudal 
vesicle abundant. Found in tissues 
and closed cavities of Herbivora and 
Onmivora, occasionally' in Carnivora. 
1. ^'esicle and head single, i. e., cyst 
monosomatic and monoce]ihalic. 

Cysticercus 
{Cysticercus 
pisiformis, larva of 
Tcenia pisiformis) 



2. Vesicles multiple, each having a 
single head, i. e., poh'somatic and 
monocephalic. 



3. Vesicles nnilti{)le, having many 
heads in each, i. e., polysomatic 
and polycephalic. 



Multiceps 

(Multiceps multiceps, 
larva of M. multiceps) 



Echinococcus 

{Echinococcus granu- 
losus, larva of E. 
granulosus) 



THE TAPEWORM LAKV^ 195 



B. Larva small. Little or no liquid in 
caudal vesicle. 



Larva firm, terminating in a tail- 
like process. 



II. Larva without caudal vesicle. 

A. Larva worm-like. Found in muscles 
of fish. 



Cysticercoid 

{Monocercus Davainece 
tetragonce, larva of 
Davainea tetragona) 



Cryptocj^stis 

(Cryptocystis tricho- 
dedes, larva of Dipy- 
lidium caninum) 



Plerocereoid 

(Larva of 
Diphyllohothrium 
latum) 

Cysticercosis (Measles) 

The presence of cysticerci in the connective tissue of muscles and 
other parts of the animal organism constitutes the condition commonly 
known as measles (cysticercosis). The disease is mainly of importance 
from the viewpoint of food sanitation, in view of the fact that measly 
beef or pork, imperfectlj^ sterihzed by cooking, when consumed by man, 
is likely to infect liim with one or moi'e tapeworms. 

The cysticerci of medical interest are, in their order of frequency: 
Cysticercus bovis of the ox, the cystic form of Tcenia saginata of man, 
Cysticercus cellulosw of the pig (also of the dog, cat, and occasionally 
man), the cystic form of Tcenia solium of man, and Cysticercus tenuicollis 
of the sheep (occasionally of the ox and pig), the CA'stic form of Tcenia 
hydatigena of the dog. 

For the development and stmcture of the cysticerci the reader is 
referred to the Life History of the Teendiise (p. 170). 

Measles of the Ox 

Taenia saginata (T. mediocanellata). Fig. 106. Tagniidse (p. 170). — 
This species, commonly known as the beef tapeworm, of which Cysti- 
cercus bovis is the larval form, lives exclusively in the intestine of man. 
The head (Fig. 109, B) is small, pear-shaped, and has four elliptical 
suckers which are frequently pigmented. There are no hooks, and in 
place of the rostellum there is a sucker-like depression. The neck is 



196 PARASITES OF THE DOMESTIC ANIMALS 

long and narrower than the head. The segments, which may number 
from one thousand to one thousand three hundred or more, are at first 
much wider than long. The complete development of the generative 
organs occurs at about the six hundredth segment, at which location 
the segments are about as long as broad. Segments containing the 
mature embr\'os reach a length of 15-20 mm. (5/8-3/4 of an inch) and a 
breadth of 5-7 mm. (1/4 -5/16 of an inch). The distal margin of each 
segment is somewhat swollen and surrounds the base of the following 
segment. The genital pores are irregularly alternate and protrude from 
the margins more and more markedly as the segments approach the 
distal end of the chain. The median trunk of the gravid uterus has 
twenty to thirty-five delicate lateral branches on each side, and these 
give off shorter secondary branches. 

The length of the entire chain may be from 3 to 12 meters (9-38 feet), 
or it may reach a nuich greater length. 



Fig. lutj. — Ta;ma sagiiiata, portiuns ul adult, — uatural size (after Boas, by Kirkaldy 
and Pollard, from Leuckart). 

The eggs (Fig. 110) are more or less globular, the shell freciuentlj' 
carrying one or two filaments. As found in the feces, the eggs often 
have the outer shell absent. 

Next to a small species — Hymenolepis nana — this is the most common 
tapeworm of man in the United States, and, in fact, with the exception 
of Diphjllohothriuni latum in a few districts, is the most prevalent 
species infesting man in other parts of the world. It is not found 
adult in other animals, and its cysticercus lives almost exclusively in 
the ox. 

Occurrence of Beef Measles. — That the beef tapeworm and its cysts 
(Cysliccrcus horhs) are more commonly met with in the United States 
than the pork tai)eworms is pi'obably due to the fact that beef is more 
often eaten rare in this country than is pork. Beef measles, therefore, 
is, in its relation to food sanitation, of the greater importance. Estimates 
made upon cattle slaughtered under Federal inspection indicate that 
nearly one per cent, of all the cattle slaughtered in the United States 



THE TAPEWORM LARV.E 197 

are affected, which, in addition to the exposure of human beings to 
tapeworm infection, is a matter involving considerable economic loss 
in the condemnation of beef otherwise of perfectly good food value. 

When it is considered that the gravid segments of the beef tapeworm 
each contain in the neighborhood of ten thousand eggs, and that eight 
to ten of these segments are usually passed by the human host each day, 
it is quite evident that, under certain not unusual conditions, the in- 
fected person could be responsible for the presence of the cysticerci in a 
large number of cattle. The chances for such transmission will be in 
relation to the location and habits of the carrier of the tapeworm. If 
it is his custom to defecate about stables or barnyards, the chance that 
some of the many thousands of voided embryos will reach their bovine 
hosts is obviously much increased. Where human excrement is used 
for soiling without its first having been made non-infective bj^ special 
treatment, cysticercus infection among cattle and hogs is especially 
frequent. 

Measles is more often found in young than in aged animals. This is 
probably explained by the fact that beef animals are usually slaughtered 
young and are more susceptible to infection during the first two years of 
their life when the tissues offer less resistance to the migration of the 
embryos. In aged animals the cysts are likely to be in a state of ad- 
vanced degeneration or entirely absorbed. 

Location and Appearance. — The cysticerci may be found in any 
organ, but are more especially to be looked for in the interfascicular 
connective tissue of striated muscle (Fig. 108). Of the muscles invaded, 
the first to be mentioned in order of frequency are those of mastication, 
chiefly the pterygoids and masseters; following these are the heart — ■ 
which is probabl,y as frequently infested as the masticatory muscles — 
the muscles of the neck, intercostals, and muscular portion of the 
diaphragm. In any case it is unusual to find the cysts numerous through- 
out the muscle, though cases occur of general invasion involving most 
of the organs of the body. 

The size and appearance of the cysts vary in relation to their age and 
stage of development. Experimental infections have shown that in 
seventeen to twenty-five days they measure 2-4 mm. (3/32-3/16 of an 
inch) in length and 1.5-3 mm. (1/16-1/8 of an inch) in breadth. They 
are grayish white in color, the outer connective tissue envelope inclosing 
a fluid which surrounds the clear vesicle or bladder worm. This is 
0.5-1.5 mm. (1/32-1/16 of an inch) in diameter, and has at one point a 
yellowish white spot indicating the location of t'he invaginated scolex 
which will evaginate on pressure upon the vesicle. 

Experiments by Hertwig have demonstrated that the cysts become 
fully developed in eighteen weeks after the occiu'rence of infestation. 
At this time he found the entire dimensions of the larger cvsts to be 



198 



PARASITES OF THE DOMESTIC ANIMALS 




Diagram of 



7 by 4.5 mm. (9/32 by 3/16 of an inch), while those of the bladder were 

G In- 4 nmi. (1/4 by 3/16 of an inch). 

Degeneration. — After a period of time, depending somewhat upon 

their location, the cysticerci undergo caseous degeneration followed by 

calcareous infiltration. That these changes may 

set in early has been shown in the experiments 

of Hertwig, who found them four weeks after 

infestation. Commonly the degenerative changes 

do not occur until full development is reached or 

for some time after. The cysticerci most likely 

to undergo early degeneration are those located 

in the heart, wlrile those of the muscles of 

mastication probably survive the longest. If 

they are found degenerated in the latter muscles, 

therefore, it is not likely that cysticerci in other 

parts of the body will be living unless they are from a later infection. 
The deg(>n<'rated cysts may be recognized by their yellowish, or some- 
times greenish color. They may be semisolid or quite gritty; pus may 

be present as a result of pyogenic or- 
ganisms gathered by the embryos in 
their migrations. The caseation, how- 
ever, may not always involve the para- 
site. In such cases the scolex is likely 
to be foimd just under the cyst wall with 
its usual characteristics retained, though 
the caudal bladder is apparently absent. 
As cysts when dissected away and ex- 
posed to the air tend to shrink by evapo- 
latioii, their stnicture is more easily 
made out if they are kept moistened 
with a drop or two of water during the 
examination. 

Vitality. — The cysts of beef measles 
natural l.y disintegrate at about three 
weeks after the death of the host, there- 
fore meat kept in cold storage for this 
Fig. 108.— Fragment of beef mus- period will not be likely to contain living 

cle, showing cysts of Cysticercus larvffi. In fresh beef all will be killed 

Lemaire"from Railliet)"^'" ^"''"" ^y the application of sufficient heat (60- 

emaire, rom ai le ;. ^^„ ^ ^ 140-156 F.) tO COok the meat 

until its cut surface presents a uniform gray color throughout. Freezing 
for a number of days will destroy them, but this method has a disad- 
vantage in that decomposition of the meat follows rapidly, making it 
necessary that it be cjuickly used. Based upon experiments by Ran- 




THE TAPEWORM LARV.E 



199 



som relative to this method, Federal meat inspection regulations provide 
that beef carcasses showing a slight degree of infestation may be passed 
for food if held for six days at a temperature not exceeding 15° F. 
(-9.44° C), as an alternative to the requirement of retention for twenty- 
one days. 

Symptoms. — Sjanptoms in bovine measles are practically niL There 
is rarelj^ a history of disturbance from the presence of the cysts, and it is 
extremely exceptional for the condition to be recognized before the 
animal is slaughtered. 

Measles of the Pig 

Taenia solium. — Tseniidse (p. 170). This species, to which Cysticercus 
cellulosce gives rise, also lives in the human intestine and is commonly 
referred to as the pork or armed tapeworm. It is smaller than T. sag- 
inata. The head (Fig. 109, A) is globular and less than 1 mm. in diam- 




FiG. 109. — "Head" of Taenia solium (A), of T. saginata (B), and Diphyl- 
lobothrium latum (C). (After Boas, by Kirkaldy and Pollard). 

eter; the rostellum is short and provided with a double crown of hooks. 
The neck is long and slender. The first segments are very short, grad- 
ually increasing in length and breadth. At about one meter (39 inches) 
from the head they are as long as broad and have the generative organs 
fully developed. Toward the distal end of the chain they measure 10- 
12 mm. (3/8-1/2 an inch) in length and 5-6 mm. (1/4 of an inch) in 
breadth. The total number of segments is from 800 to 900. The genital 
pores are more regularly alternate than in T. saginata. The median trunk 
of the gravid uterus has 7 to 12 tree-like lateral liranches on each side. 



200 



PARASITES OF THE DOMESTIC ANIMALS 



The entire length of the worm is 2-3 meters (6-9 feet), though it 
may be longer. 

The eggs (Fig. 110) are oval and provided with a very delicate shell. 
The shell surrounding the onchosphere is globular and thick. 

This tapeworm is much more rare in the United States than is T. 
saginata. In general, its distribution may be said to correspond with 
that of the domestic pig, correlated with the custom of eating the flesh 
of this anmial raw or imperfectly cooked. The cysticercus not only 
infests the pig, but may find lodgment in man himself if the eggs from 
an adult worm infesting his intestine find their way to his stomach. 






Fig. 110. — Egg of Taenia 
saginata, with outer shell and 
filaments; embryo, with em- 
bryonal shell, in center. Egg 
of T. solium (above), show- 
ing embryo with embryonal 
shell. 



Fig. 111. — Mature segment of Taenia 
saginata (left) and T. solium (right), showing 
laterally branched uterus. 

For this reason, with the added one that the 
larvae may become established in the central 
nervous system or eye, Tcenia solium consti- 
tutes a much more serious infestation than 
does T. saginata. 

A simple method for determining to which 
of these two species the infecting tapeworm 
belongs consists in clearing up a voided segment, pressing it between 
two clean slides, and observing the form of the gravid uterus as the 
specimen is held before a strong light. If the median trunk shows 
numerous delicate lateral branches on each side (20-35) it indicates 
that the infection is with Tcenia saginata. If these branches are less 
numerous (7-12) and more robust, it may be concluded that the seg- 
ment belongs to T. solium (Fig. 111). 

If treatment has resulted in the expulsion of the entire worm, an 
exact differentiation can be made by examination of the head under low 
power magnification. The pork tapeworm will show the cephalic arma- 
ture which in the beef tapeworm is absent. ''^ 
Occurrence of Pork Measles. — While the larvae of the unarmed 
tapeworm of man live only in cattle, those of the armed tapeworm may 



THE TAPEWORM LAR\.E 



201 



develop in almost anj^ mammal to which they find access. The hog, 
however, is the most common host, and, from the point of view of public 
health, the most important. 

As has been noted, the cysticercus of Tcenia solium (Cysticercus cel- 
lulosce) is a more dangerous parasite than that of T. saginata, as it may 
lodge in organs such as the brain or eye with serious consequences. 
Man can readily become a victim by auto-infection from his own armed 
tapeworm, the eggs of which may reach his stomach by way of the 
pyloris, or in being conveyed to the mouth by unclean fingers. By the 
latter means, moustache twirlers and nail biters are especially exposed. 

Fortunately, the United States is favored by the rarity of the pork 
tapeworm and consequently its cysts. Pig measles is most prevalent in 







Fig. 112. — Stages in tapeworm larval development: a, sLx-hooked larva 
(hexacanth or onehosphere) of Taenia solium ; b, cystic stage of same; c, same 
with head evaginated; d, ciliated larva of Diphyllobothrium latum; e, plero- 
cercoid of same — all enlarged (after Boas, by Kirkaldy and Pollard, from 
Leuckart) . 

districts of foreign countries where bad h^'gienic conditions prevail; 
where pigs are kept near dweUings, and their fiesh is eaten raw or im- 
perfectly cooked, conjoined with the practice of depositing human 
excrement in the open or spreading it upon the fields as fertilizer. In 
countries where sanitary control is of a more advanced standard the 
]5revalence of the pork tapeworm has been greatly reduced. 

Location and Appearance. — The muscles most often invaded by the 
cysts are those of the tongue, neck, and shoulder, then, in order of 
frequency, the intercostals, abdominal, psoas, the muscles of the thigh, 
and those of the posterior vertebral region. Organs less often infested 
are the liver, kidneys, heart, lungs, brain and eye. 

While the cj^sts may be scattered and few in number, thej^ are, on 
the other hand, sometimes present in certain locations in enormous 
numbers. Kuchenmeister in one case found one hundred and thirtv- 



^20^2 PARASITES OF THE DOMESTIC ANIINLVLS 

three in a piece of meat weighing seventeen grammes (260 gr.), — propor- 
tionatel.v eight thousand per kilogramme (2 lbs). 

More delicate and transparent than those of beef measles, the cysts 
are elliptical in form, 6-15 mm. long by 5-10 mm. broad (1/4-5/8 by 
7/32-3/8 of an inch). The wall enveloping the vesicle is a thin semi- 
transparent connective tissue membrane which, in loose connection with 
the surrounding tissue, when removed, leaves a reddened alveolar pit. 
Pressure ujjon the caudal vesicle causes the evagination of the larval 
head which, on examination by low magnification, is seen to be te- 
tragonal and to possess, in addition to the four suckers, a double crown 
of twenty-two to thirty hooks. — characters defining it as the larval 
head of Tcenia solium. 

At about twenty days from infestation the cyst shows as a delicate 
vesicle about the size of a jiin head, with the rudimentary head indicated 
by a cloudy point, and as yet without enveloping connective tissue mem- 
lirane. At the age of one hundred and ten days all of the cysts are 
approximately of equal size; the scolex is developed and lies invaginated 
into the caudal bladder. When located in organs such as the lungs, 
liver, and spleen, they often appear as grayish, caseous, calcareous, or 
])urulent nodules somewhat resembling those of tuberculosis. Differen- 
tiation can be made by careful examination which will reveal the hooks 
and often the larval heads. 

In some ca.ses a diagnosis can be made while the animal is still living 
by e.xaniination of the inferior surface of the tongue. If cysts are present 
in that organ, they will be near the base and at the sides of the frsenum, 
where they may be seen as semi-transparent, round or oval vesicles 
protruding beneath the nuicous membrane. 

Degeneration. — Degeneration of the cysts may begin at any stage 
of tiicir development, though those in the visceral organs are the first to 
mulergo these changes. The process begins with the connective tissue 
envelop and later involves the scolex. The caseous cysts present a 
gray color, while those which have become calcified are white. In the 
older degenerated cysts the changes have advanced to transformation 
into small calcareous bodies without fluid, constituting the "dry 
measles" as termed by the Initcher. In such cases the larvse are un- 
doubtedly dead. 

Vitality. — The cysticercus of pork measles is slightly more resistant 
to heat than is that of beef measles. Under post-mortem conditions it 
survives nuich longei'. Ostertag found living larva; in pork forty-two 
days after it had been slaughtered. Preservation in cold storage as for 
beef measles, therefore, will not be effectual. All cy.sts will be rendered 
harmless if the pork is cooked until its cut surface presents a uniformly 
whitish color. 

Symptoms. — Ordinarily measles of the ]iig. as in the ox, presents 



THE TAPEAYORM LAR\^E 203 

no recognizable symptoms, and, unless the cysts can be seen beneath 
the visible mucous membranes, the condition is only observed post- 
mortem. If the cysticerci l^ecome lodged in nerve centers, there may be 
such manifestations as circling movements, grinding of the teeth, or, 
possibty, convulsions and opisthotonos; symptoms which can no more 
than suggest measles as a possible cause. 

Measles of the Sheep 

Tcenia hydatigena, of which Cysticercus tenuicoUis of the sheep is the 
larval form, has been described under Cestodes of the Dog (p. 178). 

Occurrence. — Cysticercus tenuicoUis has its development under serous 
membranes of the sheep principally, but it may also. appear in other 
ruminants and in the pig. Infestation is by food and water bearing 
ova which have been spread about bj^ dogs harboring the adult worm. 

Experiments have shown that the majority of the embiyos reach the 
peritoneal cavity by wa3' of the liver. Ten days after infestation tor- 
tuous hemorrhagic trails may be found upon the surface of this organ 
under the capsule of Glisson. These are produced by the migrations of 
the parasites, and are in close relation, usually at their extremities, with 
vesicles 0.5-3.5 nun. in diameter. The head is fully developed about 
the fortieth day, and the vesicle reaches its full growth at about the 
seventh month, when it may have a diameter of 1.5-5 cm. (5/8-2 inches), 
often about the size and form of a pigeon's egg. 

These cysts ("water-balls") may be found in varying numbers, their 
size and location depending upon the age of the infestation. Their 
seat, especially in young animals, is usually beneath the serous capsule 
of the liver, though, particularly in old infestations, large bladders ma}' 
be found in most any part of the peritoneal cavity. 

As it relates to food sanitation, this cysticercus of sheep is of little 
importance. The location and size of the cysts render them easy of 
elimination from parts used as hmnan food. 

As a matter of control, it is obvious, in reference to the life history' of 
the tapeworm, that offal containing such cysts should be inaccessible 
to dogs. 

Symptoms. — Sheep measles can rarely be recognized until after the 
death of the animal. 

Cysticercus ovis. — Muscular cysticercosis in sheep has been shown 
by investigations within the past few years to be more common than 
had been suspected. It has been determined bj- Ransom that the 
cysticercus is derived from a tapeworm having its adult development in 
the dog, and not to a tapeworm of man as had been supposed. 

The following data in regard to this form of measles are quoted from 
Hall (Bulletin No. 260, U. S. Dept. of Agriculture): 



204 PARASITES OF THE DOMESTIC ANIMALS 

''Ransom's investigations showed that under careful inspection the 
percentage of affected sheep in this country has amounted to two per 
cent, or more, and that approximately twenty thousand sheep carcasses 
were retained in 1912 in al)attoirs under Federal inspection on account 
of sheep measles due to tiiis parasite. 

"The bladder worm, Cysticercus ovis, in the meat of sheep is oval and 
ranges in size from about one-third of a centimeter (one-eighth of an 
inch) to almost a centimeter (three-eighths of an inch) in length. Inside 
of this bladder there is a single tapeworm head, in which respect, as well 
as in size, this cj'sticercus differs from a h^-datid or a coenunis. Numer- 
ous cysts, however, may be scattered through the musculature, so that 
in their numbers there is a compensation, so to speak, for their small 
.size and lack of multiplicity of heads. Inasmuch as the presence of these 
cysts calls for condemnation of a part or all of the infested carcass, ac- 
cording to the degree of the infestation, and the number of carcasses 
amounts to twenty thousand a year, this parasite has considerable 
economic interest for this coiuitry, and never more than at the present 
time when the "high cost of living" is such a vital topic. 

"When one of these cysticerci from nuitton is ingested by a dog, the 
tapeworm head passes undigested to the dog's intestine and develops 
into a fairly large tapeworm, comparable to the gid tapeworm. Sim- 
ilarly', this tajieworm. Taenia ovis, i^roduces eggs which are passed 
out with the feces of the dog, and which are ingested by sheep as 
they graze over range or pasture or drink water contaminated by these 
feces. 

"The para.site has lieen found in Europe, Africa, and New Zealand. 
It has been found thus far in seven States in this country. It appears 
to be jiai-ticulaiiy prevalent in the West, a fact that is possibly- related 
to carelessness on the part of the western sheepmen as regards disposal 
of carcasses of sheep dying on the range." 

Control. — Pleasures of prevention consist in restraining dogs from 
access to the flesh of affected sheep unless it is rendered non-infective 
by cooking. Homeless dogs should be destroyed, and others going 
about where their excrement may contaminate the food and water of 
sheep should be kept free from tapeworms as a precuation, not only 
against this, but other tapeworm larv;e infesting sheep. 

CCENUROSIS, GiD 

Gid, turnsick, or staggers are popular terms applied to a disease of 
the brain or spinal cord, caused by the presence in these locations of 
the gid parasite Miilticeps )nulticeps {('oenurus cerebral is), the ccenurus 
or larval stage of the tapeworm of the dog Multiceps midticeps. Fig. 11.3 
(p. 179). 



THE TAPEWORIM LARV^ 



205 



It is observed most often in sheep, more rarely in cattle, goats, and 
other ruminants. It has been reported in the horse. 

Occurrence. — Gid is a common disease in Europe where it has been 
known for many years. The parasite has been observed in this country 
at least as early as 1901, though symptoms which were undoubted!}' 
those of gid were authentically reported from our far western flocks 
during at least ten years preceding. 
In 1909 Taylor and Boynton found 
an outbreak in a flock of sheep about 
forty miles from Ithaca, New York. 
Necropsies in these cases revealed 
the presence of the gid parasites 
from which, by feeding to dogs, 
they clami to have raised the adult 
tapeworm. This is the first authen- 
tic instance of gid in the Eastern 
United States, and the first account 
of it was given by Dr. James Law, 
of Cornell Universitj^, in a paper 
read before the New York State 
Veterinary Medical Society in the 
same year. 

In view of the large number of 
sheep and dogs which have been 
brought to the United States from 
coimtries where gid prevails, it is 
somewhat remarkable that the dis- 
ease has not been more often ob- 
served here. It is probable that nu- 
merous cases have occurred which 
have passed unrecognized and con- 
sequently unrecorded, the symptoms Fie. 113.-Portions of adult gid tape- 
being ascribed to other causes. It is worm (Multiceps multiceps), — natural size 
certain that it now has a foothold in i^"^'' Ransom from Railliet. Bull Xo. 66, 
, . , . . ^ , . , ,. Bureau An. Ind., U. &. Dept. of Agr.). 

this countrjr, m view oi which fact, 

and the further one that in other countries it is one of the most de- 
structive parasitic diseases of sheep, veterinarians and sheep raisers 
should be on the lookout for it and take proper preventive precautions. 
The Coenurus. — The completelA' developed coenurus (Figs. 114 and 
116) consists of a membraneous vesicle which may vary in size from that 
of a hazelnut to that of a hen's egg. When located on the brain it tends 
to assume a spherical form; when on the cord, which is more rare, it 
becomes adaptively elongated. The wall is thin, translucent, and dis- 
tended by a colorless fluid. On the surface of the vesicle there are little 




^206 



PARASITES OF THE DOMESTIC ANIMALS 



white, iriegiilarly grouped spots, each representing an invaginated larval 
tapeworm head. These vary in degree of development and in number 
from four hundred to five hundred, and herein lies an essential differ- 
ence between ccenurus and cysticercus, the latter containing but one 




Fig. 114. — Diagrammatic section of Ccenurus; a, normal dis- 
position of scolex; b. c, d, e, diagrammatic representation to show 
the homology between cysticercus and ccenurus (after Ransom, 
from Railliet, Bull. Xo. G6, Bureau An. Ind., U. S. Dcpt. Agr.). 




Fig. ll."*. — liraiii of lainlt. showing the furrow.s pro- 
duced by the miKration of the young gid bladderworms, 
taken at a time immediately following the period of 
invasion — i. e., from fourteen to thirty-eight days after 
infestation. — natural size (after Ransom, from Leuck- 
art. Bull. No. 66, Bureau An. Ind., V. S. Dept. Agr.). 



Fig. 11(1. — tiid bladderworm 
showing immature tapeworm 
heads, — natur.al size (after 
Ransom, from Railliet, Bull. 
No. 66, Bureau An. Ind., U. S. 
Dept. Agr.). 



head. In some cases the heads may be found evaginated to the surface 
of the vesicle (Davaine), when the cerebral disturbance bj^ pressure is 
contributed to by the direct irritation fiom the booklets. 

Development. — Animals susceptible to gid become infested by eggs 
of the tapeworm MuUiceps multiceps which is harbored by dogs. The 
eggs and gravid segments, spread about as they are, will, in the presence 



THE TAPEWORM LARV.E 207 

of moisture and favorable temperature, retain their power to infect 
for several weeks. In dry locations and under the influence of a hot 
sun the period of their vitality is reduced, probably to a few days at 
most. Eggs, through the mediation of food and water, reaching the 
digestive juices of sheep and cattle have their shells dissolved, setting 
free the contained embryos which, on reaching the intestine, penetrate 
its walls by means of their hooklets. From here it is probable that they 
are passively carried to other parts of the body by the blood and lymph 
currents. With rare exception, only those embiyos which reach the 
brain or spinal cord continue their development. 

The central nervous system is reached by the embryos about the 
eighth day after the occurrence of infection, upon the arrival at which 
location they lose their hooklets and transform into small cysts. In the 
course of their burrowings along the surface of the brain they leave 
small sinuous tracks which may be found three to five weeks after in- 
fection, often marked by a yellowish purulent material (Fig. 115). At 
the termination of these furrows the young bladderworms become 
stationaiy, and their development proceeds. 

In five to six weeks the cysts are about 1 cm. (3/8 of an inch) in diam- 
eter and the heads have begun to appear, these attaining their full 
development in ten to thirteen weeks. The cysts continue to grow 
until they have reached a diameter of from 3 to 5 cm. (1 3/16 to 2 inches), 
during which time new heads are in process of formation (Fig. 116). 
Heads in various stages of development, therefore, may be found in the 
same vesicle. 

Tabular Review of Life History of Mttlticeps Multiceps 
Adult Tapeworm in intestine of dog. 

Egg. — Expelled from intestines. 

Hexacanth. — Freed from egg in digestive tract when 

I ingested by sheep. 

Acephalocyst — In brain or cord of sheep. 

V Ccenurus (Polycephalic cyst). — Same. 

Scolex. — -Attached to intestinal wall of dog after in- 

I gestion of cyst. 

•Adult Tapeworm. — In intestine of dog. 

Post-mortem Appearance. — In chronic cases there are usually one 
or more cj^sts, rarely as many as six, though cases are recorded in which 



-208 PARASITES OF THE DOMESTIC ANIMALS 

there were moie than twice this number. The lesions produced will 
differ according to the development attained by the parasites at the 
time of the examination. Primarily the lesions are disseminated, and 
the small cysts may be found at various places upon the convex surface 
of the brain, surrounded by a yellowish exudate, granules, and cal- 
careous particles, while, in the vicinity, there may be a small hem- 
orrhagic area. In cases which have presented the characteristic symp- 
toms of turnsickness, or gid jiioperly so-called, but one large vesicle of 
advanced develojjment is ordinarily found (Fig. 116). Such cysts are 
usuall.v located upon the surface of the cerebral hemisphere, where, 
bj' their pressure, they produce an anaemia and softening of the cortical 
substance. In old cases with large cysts situated upon the brain's .sm-- 
face the constant compression upon the roof of the cranium may, by 
ab.sorption, bring al)out thinning of the bone to such a degree that it 
will yield to even comparatively slight pressure of the fingers. 

Exceptionally, the coenurus may be found free in an excess of fluid 
in a lateral ventricle, and, again rarely, exploration of the vertebral 
canal will reveal a cyst in the lumbar or cervical region, or it may be 
at the medulla oblongata. Such cysts are much elongated, and usually 
there is but one. At the cyst's location the medullary '.sul^stance is 
atrophied and .softened. Such muscles as may be secondarily involved 
show the alterations of atrophy and cachexia. 

Symptoms. — As may be inferred from the foregoing, the symptoms 
l)resenled in cocnurosis will be conditional upon the age of the infection 
and the size attained by the cj^sts, and also ujion their location, the 
latter factor fm-nishing the two forms of the affection, — the cephalic, 
when located in the brain, and the medullary if in the vertebral canal. 

If the parasites are few in number, there will be no symptoms during 
the early stages, or they may be slight and unnoticed. If there is a 
heavy invasion the cerebi-al disturbances caused by the migrations of the 
parasites may be manifested as stated below. According to Moller, 
however, these jirimaiy .symjitoms are not otiserved in four-fifths of 
the cases. 

Early in the infestation there is dullness, somnolence, inapjietence, 
and usually a rapid loss of flesh. Visual distiu'bance is soon noticed, the 
animal colliding with objects which it is apparentl.v unable to see. 
]^xamination of the eyes at this time will show a congestion of the 
sclera; later there is strabismus with either convergence or divergence, 
and the pupils may he unequally dilated. There are concomitant 
troubles of motility, and, as the disease progresses, the animal frequently 
falls down or may assume a recumbent position for the entire day. 
If it becomes unable to rise, it is probatjle that death will soon follow. 

^V'^len these early s_\niiijtoms occur, they generally first appear ten 
to twenty days after infection and persist for a variable period of two 



THE TAPEWORM LARV.E 209 

to ten days. They then subside, and, during a following latent period 
of four to six months, it is only by close observation that anything 
abnormal about the anunal can be detected. The ocular disturbances 
already referred to then appear; the head is held in a pecuUar position, 
and the animal turns in circles or it may stagger and stumble about, 
repeatedly falling. The movements are made in an impulsive manner, 
with feet lifted high, and the turning may be to the right or to the left, 
usually toward the side on which the brain is compressed. Other move- 
ments than turning may be exhibited, and, in fact, their character will 
depend upon the part of the brain affected by the cyst. 

These sjanptoms are not continuous, appearing several times during 
the day with intervals of comparative repose. In three to six weeks 
from their onset the animal passes into a state of complete paralysis 
and dies from exhaustion, or it may be in convulsions. 

Such characteristic phenomena of gid are of the final stage, and are 
due to the pressure of the fully developed coenurus upon the brain and, 
in part also, to direct irritation from the booklets of the parth^ evag- 
inated larval tapeworm heads. It is only at this stage that the turning 
movements appear, therefore the disease does not trul.y merit the name 
of gid or turnsickness until these manifestations are reached. 

In gid of the spinal cord the parasite is usually located m the lumbar 
region. The chief symptom is a graduallj' increasing weakness and 
paralysis of the hind quarters (hydatic paraplegia). The bladder and 
rectum become involved and the animal becomes progressively weaker 
and emaciated. Death occurs in general debility and exhaustion after 
a course of one to three months. 

The sjanptoms of gid in other animals are of the same general char- 
acter as those in sheep. 

Control. — Reviewing the knowledge possessed as to the etiology of 
gid, the measures to be followed for its eradication are suggested. 
Chance infection of dogs by the tapeworm should be removed by burn- 
ing the heads harboring the cj'sts, or by cooking the affected brains if 
they are to be fed to these animals. Dogs kept in the vicinity of animals 
susceptible to gid should be given tseniafuge treatment every three 
months (p. 186). During the operation of this treatment they should 
be confined and the expelled worms, fragments, and feces collected and 
burned or deeply buried. 

Gid is a further contribution to the accumulating reasons why un- 
cared for and unnecessary dogs — numerically limitless in most commu- 
nities — should be destroyed. 

Treatment. — On account of the inaccessible location of the parasites, 
treatment, except by surgical means, is useless. The operative measure 
consists in trephining the cranial cavity and removing the ccenurus, 
but this can only be advised as practical in the case of animals having 



210 PARASITES OF THE DOMESTIC ANIMALS 

an especial value. Cold packs upon the head or continuous irrigation, 
accompanied liy purgatives, have been recommended for the acute 
stage, but such treatment can be no more than palliative, and is scarcely 
practical luiless under exceptional conditions. 

In general, it is better, from considerations of economy, to slaughter 
animals upon the first evidence of gid. 

Echinococcosis 

Hydatid Disease. 

Hydatid disease is caused by the presence of Echinococcus granulosus 
(E. polijinorphus, E. multilocularis, etc.) or so-called hydatid, the cystic 
stage of the tapeworm of the dog, — Echinococcus granulosus (Tcenia 
echinococcus), elsewhere referred to under the cestodes of that animal 
(p. 181). It occurs in man and all of the domestic manunals, the hy- 
datids usually located in the organs of the abdominal or thoracic cavity, 
most often the liver, though not infrequently the lungs, spleen, serous 
membranes, and other organs, several of which may be affected in the 
same animal. The disease is as cosmopolitan as dogs and their par- 
asites, therefore it is of world-wide prevalence. 

The Echinococcus (Fig. 1 17). — While the echinococcus is the largest 
of the ta])('woriii cysts, the dog tapeworm, of which it is the larval form, 
is but 5 mm. (3/16 of an inch), or thereabouts, in length, and consists 
of a head and three segments. When uninfluenced by pressure, the 
echinococcus c> st is more or less spheiical in sha]De and presents a com- 
plex stru('ture, the parts of which may be set forth for study as follows: 

1. An external cuticulai' membrane (hydatic membrane). 

2. An internal germinal membrane. 

3. The fluid which distends the vesicle. 

4. The luoligeious vesicles, which contain the larval tapeworm heads. 

0. The (laughter vesicles. 

Surrounding the whole is a capsule formed from the connective 
tissue of the organ in which the structure is lodged. 

1. The cuticular membrane limits the echinococcus externally. It 
is whitish in color, concentrically laminated in structure, and in large 
vesicles may attain a thickness of 1 mm. 

2. The germinal membrane is much thinner than the cuticular, 
usually- not exceeding 20-25 microns in thickness. On its internal sur- 
face there appear groups of small papilke, representing the beginning 
development of the jn-oligerous vesicles. 

3. The hydatic fluid is colorless or yellowish and in reaction is neutral 
or slightly acid. It may contain a number of substances, mostly de- 
rived by endosmo.sis from the blood and hnnph of the organ invaded. 

4. The prnlifrerous vesicles appear on the internal surface of the 



THE TAPEWORM LARV.E 



211 



germinal membrane when the mother vesicle has developed to a suffi- 
cient size. At first papillarj^, each has a cavity that graduallj' enlarges, 
and the vesicles thus formed have an attachment to the germinal mem- 
brane by a short pedicle. Within each there develops a variable num- 
ber — usuallv five to twenty or more — of little oval bodies. These are 




Fig. 117. — Diagram of Echinococeus hydatid: cu, tliick cuticu- 
lar membrane; gr. germinal membrane; a. b., development of 
proligerous vesicle; c, development of the heads according to 
Leuckart; d, development of heads according to Moniez; e, fviUy 
developed brood capsule with heads; f, brood capsule has ruptured 
ai)d the heads hang into the lumen of the hydatid; g, liberated 
head floating in the hydatid; h, i, k, 1, m, formation of secondary 
exogenous daughter cyst; n, o, p, formation of endogenous cyst, 
after Kuhn and Davaine; q, daughter cyst with one endogenous 
and one exogenous grand-daughter cj'st; r. s,, formation of en- 
dogenous daughter cysts, after Naunyn and Leuckart; r, at e.x- 
pense of head; s, from brood capsule; t, constricted portion of the 
mother cyst (copied from Osborn's "Economic Zoology," after 
R. Blanchard; Bureau An. Ind., U. S. Dept. Agr.) 

the larval tapeworm heads. When completely formed the heads meas- 
ure slightly more than 0.1 mm. and show the suckers and double crown 
of hooks. 

5. Daughter or secondary vesicles similar in character to the mother 
vesicle have origin in the hydatic membrane which the}' distend and 
finally rupture, falling into or outside of the mother vesicle. In the 
first case thev are termed endogenous vesicles, in the second exogenous 



212 PARASITES OF THE DOMESTIC ANIMALS 

vesicles. The exogenous vesicles are capaljle of implantation upon 
organs somewhat remote from the primary vesicle. This occurs more 
commonl}- in the pig and ruminants than in man. 

The daughter vesicles may, in the same manner, give oE grand- 
daughter vesicles which, like the parent vesicles, may be endogenous 
or exogenous. 

All of these vesicles develop proligerous vesicles and consequenth' 
the larva! tapeworm heads, or they may remain sterile, in which case 
they are referred to as acephalocysts. 

It will be noted from the foregoing that one onchosphcre may develop 
hundreds of tapeworm heads. 

The echinococcus is usually considered as one species, though there 
is a form which has received the name of Echinococcus midtilocularis 
(E. alveolar is), thought to be due to a tapeworm affering slightly from 
E. granulosus. Its main distinguishing character is the size of the 
vesicles, which does not exceed that of the pea. They have a honey- 
comb ai'rangement, and are filled with a gelatinous material, the majority 
of the cysts remaining sterile. The mass of vesicles ma.y grow to the 
size of a child's head, and constitutes a very fatal form of echinococcosis. 
It has been foimd in the ox and pig, but more frequently in man. 

Development. — Embryos finding their way to the intestine with 
food (ii- \\ ;ilcr that has been contaminated with egg-containing excrement 
of dogs are i)rnl)at)ly carried to the liver by the portal system. Four 
weeks after infecting pigs, Leuckart found small white nodules about 
1 mm. in diametei', each with a capsule derived from the hepatic con- 
nective tissue, and containing within it the globular echinococcus. At 
about five months the cysts were the -size of a hazelnut, and each con- 
tained a thick-walled whitish-colored vesicle, — the mother vesicle. 

The development of the echinococcus is slow. It may remain simple 
and its growth be limited to increase in volume and thickening of the 
cuticular membrane, in which case it may reach a diameter of 15 cm. 
(6 inches). Generally its size does not exceed that of an orange, and its 
growth is attained by the formation of secondary vesicles. Where these 
pass to the inside of the mother vesicle this becomes dilated in an irreg- 
ular manner, influenced .somewhat by the compression of the adjacent 
organs of the host (Fig. 117). 

As regards the formation of the daughter vesicles, the process has 
usually been described as a normal one following the complete develop- 
ment of the hydatid. D6ve, in a paper upon this subject (1917), states 
that every multivesicular cyst is one which has had its vitality menaced, 
and that the endogenous vesicles are the result of a defense reaction. 
The simple cyst with its brood capsules, according to this authority, 
represents the normal hydatid. 



THE TAPEWORM LARV.E 213 

Tabular Review of Life History of Echinoco^cus Granulosus 
Adult Tapeworm. — In intestine of dog. 

Egg. — Expelled from intestines. 

T 

Embryo. — Released from egg in digestive tract after 
I ingestion by pig, ruminant, or other 

I mammal. 

Mother Vesicle (Hydatid). — In liver or other organ of 

same. 
Daughter Vessicles 

Scoleces. — Attached to intestinal wall of dog 
I after ingestion of brood capsules con- 
I taining larval heads. 
Adult Tapeworms. — In intestine of dog. 

Regarding the longevity of the hydatids, such information as is pos- 
sessed is furnished mainly by cases of hydatid disease occurring in man. 
A case is recorded of the persistence of an echinococcus cyst in a horse 
for seven years. Usually when found in lower animals it is in those 
slaughtered for food, and in most such cases the animals are not old 
enough for the hydatids to have reached their full development. It is 
probably for this reason that the disease is clinically unobserved or is 
much less serious in these animals than in man where the hydatid devel- 
opment remains uninterrupted. 

The human evidence seems to indicate that the longevity of the cyst 
may be only limited by that of its host, for a case is recorded where it 
had existed for thirty-five years and another where the swelling had 
gradually spread over the face for forty-three years, and when operated 
upon had attained the size of a cliild's head. 

Post-mortem Appearance. — Hepatic echinococcosis is accompanied 
bj'' considerable alteration. When the cyst is large the liver becomes 
hypertrophied and its weight may be increased as much as ten times 
that of normal. The increase in volmiie ma.v compress neighboring 
organs, hindering their function and displacmg them. The diaphragm 
especially is crowded and pressed forward upon the lungs. The surface 
of the liver has protruding elevations of various size and number, and 
Glisson's capsule is noticeably thickened, perhaps forming adhesions 
with contiguous organs. Section of the organ reveals cavities of un- 
equal size from which the hydatic liquid with contained vesicles flows 
out. The connective tissue capsules of the cysts will vary in thickness 
from 3 to 10 mm. (1/16 to 3/8 of an inch). These capsules are structurallj^ 



214 



P.4JIASITES OF THE DOMESTIC ANIMALS 



somewhat compact, and are generally little adherent to the wall of the 
hydatid. 

Old hj'datids may become considerably modified or completely 
destroj'cd. In such cases the walls are much thickened and show 
degenerative changes. The fluid diminishes and disappears with the 
contraction of the cavitj', the degenerative material in the walls be- 
comes more dense, there is calcareous infiltration, and, finally, the 
hydatid may be transformed into a calcareous mass. 

Symptoms. — The symptoms of hepatic echinococcosis in lower 
animals arc, as a rule, too vague for recognition of the specific affection; 




Fig. 118. — Echinococcus granulosus 
with brood capsules (after Leuckart). 



with fibrous sac i;iid back, showing hydatid 



it usually remains for post-mortem examination to establish the diagno- 
sis. Pulmonary echinococcosis is generally accompanied by the hepatic 
form, and may exhibit respiratory disturl)ances, as accelerated respira- 
tion and dyspnoea, — STOiptoms which may be contributed to bj' pressure 
•of the enlarged liver upon the diaphragm. In the region invaded by the 
hydatid the vesicular murnuu- is lessened or wanting, while in parts 
nearby it is increased. Percussion will generally definitelj' establish 
its location. 

Hydatid disease rarely progresses to a fatal termination in lower 
animals. 

Control. — As the tapeworm from which the echinococcus is. derived 



THE TAPEWORM LARV.« 215 

is harbored by the dog, rarelj' the cat, infection of man and domestic 
animals is by the dissemination of the eggs of this tapeworm witli the 
excrement of its hosts. It follows that all hydatic viscera in slaughter- 
ing establislmients or elsewhere should at once be destroyed by burning, 
thus preventing the larval tapeworm heads from reaching the intestines 
of dogs and cats. Where the disease has appeared it is a good precau- 
tionary measure, though often impractical, to administer tteniafuge 
treatment (p. 186) at repeated intervals to all dogs in the vicinity. 
During the treatment the animals should be confined where their fecal 
material can be carefullj' collected and burned. 



CHAPTER XVIII 
PHYLUM III. CCELHELMIXTHES 

The Smooth axd Segmented Roundworms 

The C«lhclniinthes are distinguished from all of the worms thus far 
considered by the presence of a coelom, or body cavity located between 
the outer body wall and the intestine. With the exception of the thorn- 
headed worms, the digestive tract is complete, and there may or may 
not be a closed l)lood circulation. Excretory vessels connect the cavity 
of the body with the outside. The body muscles are "epithelial muscle 
cells" developed from the outer epithelial wall of the coelom. Sub- 
groups exhibit distinct differences in the character of the coelom. In 
the Aimelida, to which the earthworms belong, it is segmented, the 
segments (somites) corresponding to the annulations or ringing of the 
bodj' wall. In the Nemathelminthes, which includes most of the par- 
asitic species, there is no segmentation of the body cavity or annulation 
of the body wall. In the Hirudinea, the annulated group which con- 
tains the leeches, the coelom is Init slightly developed, and usually the 
annulations outmnnber the somites. 

The phylum Ccelhelminthes has the two classes named below for 
discussion in this work, the first containing all of the endoparasitic 
worms which remain to be considered, while of the second, only the 
leeches are of direct para.sitic interest. 

Class I. Xemnthelminthes. — Body without external or internal seg- 
mentation. 

Class II. Annelida. — Body with external and internal segmentation. 

Cl.\ss I. Nemathelminthes 

Coelhelminthes (p. 216). — This group contains the roundworms, or 
so-called threadworms, though not all are filiform. There are both 
free and parasitic forms, examples of the former living under stones 
and in other moist places. The parasitic species are by far the more 
numerous and important. 

The body is elongated, and, in being cylindrical, differs from that of 
the Platyhelminthes which is ilat, while the absence of annulations and 
segmentation distinguishes it from that of the Annelida. 

The class includes two parasitic orders. The first contains the typical 



CCELHELMINTHES 



217 



representatives of the class and, with the exception of the thorn-headed 
worms, all of the species of medical interest. 

Order I. Nematoda. — Alimentary canal present. 

Order II. Acanthocephala. — Thorn-headed. Alimentary canal ab- 
sent. 

Order I. Nematoda 

Nemathelminthes (p. 216). — The order Nematoda includes numerous 
species having a wide distribution as parasites of animals and plants. 
The outer surface of the 
body is covered by a 
tough chitinous cuticle 
which is secreted by an 
underlying layer corre- 
sponding to the epithe- 
lium and derma. The 
cuticular surface may be 
plain, striated, or more or 
less mottled. Transverse 
section of the body wall 
shows four thickenings — 
two median and two 
lateral — corresponding to 
the dorsal, ventral, and 
lateral lines which are 
disposed longitudinally. 
Within the lateral thick- 
enings are contained the 
two excretory vessels 
which, in the vicinity of 
the head, unite by a 
transverse commissure 
reaching the exterior on 
the ventral surface. The 
muscles are a laj^er of 
vesicular cells derived 

from the epithelium of the outer coelomic wall. They are divided bj^ 
the lateral and median Hues into four fields, and so project into the 
coelom as to occupy considerable of its space (Fig. 119). 

The digestive system is simple and complete, beginning with the 
anterior terminal mouth and ending in an anus which is ventral and 
close to the caudal extremity of the bod3\ A muscular esophagus suc- 
ceeds the mouth, soon expanding to form a bulbous sucking organ 
lined throughout with a cuticular layer. From this j^oint to the 




Fig. 119. — Transection of body of Ascaris equi (fe- 
male), showing cuticular wall, muscle cells and proto- 
plasmic processes extending into coelom, transversely 
cut portions of ovary and uterus, and intestinal canal in 
center (from microphotograph by Hoedt). 



218 



PARASITES OF THE DOMESTIC ANIMALS 



anus the alimentary canal is usually a uniform tube with little oi' 
no flexion. 

The nervous system consists of a nerve ring surroiuiding the esophagus, 
and of the nerves given off from this ring passing forward and back, 
the largest of which are in the dorsal and ventral lines. Along the course 
of these nerves there are ganglionic cells, but there is no massing to form 
true ganglia as occurs in the Aimelida. 

The sexes are usually separate, hermaphroditic forms occurring 
among free-living species. In general, the females attain a distincth' 

greater length and thickness of 
the body than do the males, and 
in other respects they can easily 
be distinguished. The males are 
visually provided with chitinous 
coj^ulatory organs known as 
spicules. These are curved, 
spine-like structures which lie 
in a sheath close to the anus, 
and they can be protruded or 
retracted through the cloacal 
opening (Fig. 120). They are 
usuall>- two in number, but 
there may be but one. The 
character of the spicules often 
sei"\'es as a guide in the estab- 
lishment of relationships of cer- 
tain groups. Surrounding the 
spicules there is, in some forms, 
a membraneous expansion which 
is i-efei'retl to as the caudal bursa 
or pouch. This structure is best 
develoi)cd in the Strongylidse, 
where its varied characteristics 
furnish an aid in the recognition 
of species. The bursa is a clasp- 
ing organ used in coijulation, while the spicules serve to direct the course 
of the .semen. In the female there is a special genital opening, — the 
vulva, located on the ventral anterior half of the body, or it may be to- 
ward the anus, its position varying according to species. The cylindrical 
body is usually more or less distended with eggs, and frequently the 
egg-packed uteri can be distinctly seen under low magnification and 
transmitted light. 

The internal reproducti\-e sj-stems of the male and female are much 
alike. In l)ofh they are long tubular organs, coiled forward and back, 




Fig. 120. — Posterior e.xtn'init.v of male iicnia- 
todc; diaRraniniatic longitudinal section: cl, 
cloaca; d, intestine; ni, retractor niu.scle of 
spicule; s, sheath of spicule; w, bod.v-wall (after 
Boas, by Kirkald.v and I'ollnrd). 



CCELHELMINTHES 219 

and lying loosely in the ccelomic cavity. In the male this genital tract 
is always single, the finer part of the tube constituting the testis, the 
heavier remaining portion serving as a seminal vesicle and terminating 
in the duct. The ovaries and uteri are likewise continuous structures, 
the former being constituted by the finer portions, while the uteri are 
usually much distended (Fig. 119). In certain forms there is but one 
genital tube in the female, but in most all there are two which unite 
close to the external opening to form the vagina. There is no distinct 
vitellarium as in the flatworms, the ovary assuming the function of this 
gland. 

The eggs are usually globular or ovoid in shape; as there is copulation, 
they are fertilized in the uterus. Following this the development ma.y 
or may not take place while the eggs are retained. 

As to the terms oviparous and ovoviviparous, frequentlj^ used in 
summarizing the characteristics of parasitic groups, it may be well to 
direct attention here to their correct apphcation. 

The term oviparous is properly applied to the oviposition of eggs 
which undergo incubation after they have been oviposited, or to the 
oviposition of eggs which have been incubated within the genital cavity 
of the female and at the time they are oviposited contain embrj^os more 
or less developed. 

The word ovoviviparous is commonly used in reference to the oviposi- 
tion of eggs containing embryos developed and ready to emerge at the 
time the eggs are extruded, as might be in the last-stated case. It is 
more correctly applied where the embryos, having been developed, 
escape from the eggs while these are still within the body of the female. 

In other words, the escape of the embryos from the eggs occurs out- 
side of the bod3^ of the parent in the oviparous method, within the parent 
body in the ovoviviparous. 

The term viviparous, often apphed in biology for ovoviviparous, 
has reference to the tj^pical mammalian method of gi^'ing birth, where 
the egg is not concerned in this process, and there is consequently no 
hatching. 

Parasitism of the Nematodes in General 

In most of the nematode parasites there is a post-embr\-onic free 
existence, the infection of the host being direct and necessarj' to the 
parasite's sexual maturit}'. A notable exception is furnished by Trich- 
inella, where there is no period of free life, the transfer from host to 
host being accomplished by the ingestion of food containing the encj-sted 
larvae. 

The degree of injury to their hosts by the nematodes varies consider- 
ably and is frequentlj' not characteristic. In general, it may be said 
to depend upon the numlDer of the parasites present, Ijut the seriousness 



2-20 PARASITES OF THE DOMESTIC ANIMALS 

of their effect does not depend upon this wholl.y. A relatively light 
invasion with forms which elaborate toxins possessing a high degree of 
toxicity may have a more deleterious influence upon the health of the 
animal than a heavier infestation with worms from which the elimina- 
tions are less toxic. Again independent of numbers, adult worms or 
their larva can, by their migrations, set up in their unusual locations 
sei'ious inflanmiatoiy and degenerative changes which may be of an 
infective character due to the bacteria which they transport. 

Intestinal worms which attach to the mucosa are far more capable 
of producing serious effects than those which live free in the intestinal 
contents. The former live upon the tissues of their host and cause at 
their attachment a wound through which infection may readilv enter, 
while the latter obtain their nourishment from the partlj^ digested 
alirnentaiy material and do not directly lacerate the mucosa. 

Location is a main pathogenic factor. This may be accidental by 
active or passive migration, as in the case of adult or larval filarise, 
which seem capable of wandering to most any part of the body, or it 
may be specific, certain nematodes normally infesting only the intestines, 
others the respiratory tract, while some occupy the blood vascular 
system in their larval state or both as larvae and adults. Again, Trich- 
ineUa npiraUs causes its most serious disturbance duiing the migration 
of the embryos through the musculature of its host. In general, it may 
be said tiiat nematode invasion of the intestines is less .serious than that 
of the respiratory tract. The injurious effects from verminous parasitism 
of the blood are usually due to injury to the vascular walls, or, if the 
worms are numerous and massed, to interference with the blood flow. 
Following uiDon tliis there may be the production of a thrombus and 
fornuition of emboli with the subsecjuent development of aneurism. 
AVhile parasites in the blood in any case constitute a .serious infection, 
the greater number of specific conditions due to such parasitism are 
caused by Ijlood-invading Protozoa. 

The sjjecific limitations as to host of the pai'asitic worms is probably 
nuich influenced l\v the character of the nutriment with which the}^ are 
supplied in each particular case. Certain hosts having no more than a 
class relationship may harbor intestinal worms of the same species, but 
are more likely to do so if there is a measure of similarity in the char- 
acter of the hosts' alimentation. This is exemplified in the distinctly 
omnivorous animals, man and the pig, each furnishing hostage for the 
intestinal worms Ascaris lumhricoides {A. suts) and Giganiorhynchus 
hirudinaceus, while, again, the carnivorous dog and cat both harbor 
Belascai'is marginata and Ankylostoma canina. 

Opportunity is also a factor. Animals of similar diet are ahke exposed 
to infection by food specific for or most likely to be contaminated with 
larviE or eggs of certain species of parasites. Such parasitism as the 



C(ELHELMINTHES 221 

invasion of the intestines of man by the tliorn-lieaded worm of the pig 
{Gigantorhynclms hirudinaceus) is regarded as stray or accidental, but 
if the grub of the Maj^ beetle, the larval host of this worm, constituted 
a choice morsel of diet for man as it does for the pig, it is probable that 
the thorn-headed worm would much more freciuently inhabit man's 
intestines. 

Adaptive modifications from a free to a parasitic life, and adaptations 
of the parasite to differing host environments, or to new locations taken 
up in the body of the same host, are best exemplified in the Protozoa. 
In the more complexly organized worms the faculty of adaptation is 
possessed in less degree; though undoubtedly the parasitic forms have 
without exception passed through at least the first of the gradations 
mentioned. The adult nematodes infesting the respiratory tract, as 
Dictyocaulus filaria of sheep, and those infesting the blood vascular 
system, as Dirofilaria immitis of the dog, have probably reached these 
regions from a primary parasitism in a less obscure part of the body, 
the adaptivity having become sufficiently fixed that the conditions 
supplied by the location later acquired are now specifically essential 
to their sexual development and reproduction. 

Treatment in General. — Treatment in nematode helminthiasis has 
in view primarity the expulsion of the worms, and secondarily the 
building up of the general health of the animal. Anthelmintics act by 
destrojang or in some way so affecting the worms that they are easih' 
expelled from the body. An agent capable of killing the parasites may 
have a like effect upon the host if used without due precaution; in any 
event it is likely to be too drastic and cause an acute disturbance more 
serious than the subacute one which it is sought to remedy'. In the 
case of intestinal worms, remedies which reduce them to a sufficiently 
passive state that they may be readily swept out by the action of a 
purgative are to be preferred; and here the effect of the vermifuge 
upon the host, as compared with that of a true vermicide, is one 
of degree, and the tolerance of the patient is to be taken into con- 
sidei'ation. 

Essentially the success of vermifuge treatment will be influenceil by 
the loca:tion of the worms; only those in tubular organs in communica- 
tion with the outside can be reached by such medication, while its action 
will be hampered in the case of those which burrow into and attach 
upon the mucous lining. 

It has been said that it may be taken as an axiom in hehninthology 
that each woim in the bodj^ develops from an egg or larva which has 
entered from without. Worms do not go on multiplying indefinitely 
with the production of new adult generations in the same host. The 
degree of the infestation, therefore, depends ijrimarily upon the degree 
of contamination of food or water taken in bv the animal, and seeondarih- 



2^2 PARASITES OF THE DOMESTIC ANIMALS 

upon the susceptibility and favorable hostage offered b.y the individual 
to the parasite. 

It follows that preventive measures should be based upon the Ufa 
histoiy of the species to which such measures are applied. Where 
this is known antl intelligenti.v taken advantage of, the problem of the 
eradication of the parasites becomes much easier of sohition than it 
otherwise would be. For the same reason, more detailed reference to 
control is reserved for application to particular cases in the pages to 
follow. 

The nematode parasites are to be considered under seven families 
having marked differences as to parasitic habit and also as to degree 
of injury which they cause in their hosts. These are as follows: 

Family I. Ascaridse. 



Family 


II. 


Oxjiuida?. 


Family 


III. 


Hcterakidffi. 


Family 


IV. 


Filariidse. 


P'amil}^ 


V. 


Strongylida;. 


Family 


VI. 


Eustrongylidae. 


Familv 


VII. 


Tiichincllidse. 



Classification of Parasites of the Phylum Ccelhelminthes 

Phylum III. Ccelhelniinthes. P. 216. 

Class A. Nemathehninthes. Smooth-lwdied roundworms. P. 216. 
Order 1. Nematoda. P. 217. 
Family (a) Ascarid». P. 229. 
Genus and Species: 

Ascaris equi. Host, equines. P. 233. 
Belascaris marginata. Host, dog, cat. P. 237. 
To.xascaris limbata. Host, dog. P. 238. 
Ascaris lumbricoides. Hosts, man, hog, sheep. P. 239. 
A. vitulorum. Host, cattle. P. 241. 
Family (b) Ox^inidse. Seat worms. P. 23.5. 
Genus and Species: 

Ox^airis equi. Host, equines. P. 235. 
Family"(c) Heterakida?. P. 242. 
Genus and Species: 

Heterakis jiprspicillum. Host, poultry. P. 242. 
H. vosicularis. Host, poultry. P. 242. 
Family (d) Filarii(te. P. 244. 
Genus and Species: 

Setaria labiato-papillosa. Host, equines. P. 244. 
Habroneina megastoma. Host, equines. P. 245. 
H. microstoma. Ho.st, equines. P. 246. 



CGELHELMINTHES 223 

Gongylonema scutata. Hosts, sheep, cattle. P. 247. 

Filaria labiato-papillosa. Hosts, cattle, deer. P. 248. 

Dirofilaria immitis. Host, dog. P. 248. 

Spiroptera sanguinolenta. Host, dog. P. 250. 

Arduenna strongylina. Host; hog. P. 251. 

Physocephalus sexalatus. Host, hog. P. 252. 

Dispharagus spiraUs. Host, poultry. P. 254. 

D. hamulosus. Host, poultry. P. 254. 

D. nasutus. Host, poultry. P. 254. 

Tetrameres fissispina. Host, poultry. P. 254. 
Family (e) Strongylidae. P. 255. 
Genus and Species: 

Stephanurus dentatus. Host, hog. P. 295. 
Subfamily (a) Metastrongylinee Worms of the respiratory tract. 
P. 256. 
Genus and Species: 

Dictyocaulus filaria. Hosts, sheep, goat. P. 256. 

Synthetocaulus rufescens. Hosts, sheep, goat. P. 257. 

S. capillaris. Hosts, sheep, goat. P. 258. 

Dictyocaulus viviparous. Host, cattle. P. 259. 

Metastrongylus apri. Host, pig. P. 260. 

M. brevivaginatus. Host, pig. P. 260. 

Dictyocaulus arnfieldi. Host, equines. P. 261. 

Hsemostrongylus vasorum. Host, dog. P. 261. 

Synthetocaulus abstrusus. Host, cat; P. 262. 
Subfamily (b) Trichostrongylinse. Worms of the stomach and 
intestine. P. 268. 
Genus and Species : 

Hasmonchus contortus. Hosts, sheep, goat, cattle. P. 268. 

Cooperia curticei. Hosts, sheep, goat. P. 268. 

.Ostertagia marshalli. Host, sheep. P. 269. 

Trichostrongj'lus instabilis. Hosts, sheep, goat. P. 271. 

Ostertagia ostertagi. Host, cattle. P. 272. 

Nematodirus filicollis. Hosts, cattle, sheep, goat. P. 273. 

Cooperia oncophora. Hosts, cattle, sheep. P. 275. 
Subfamily (c) Strongylina. Worms of the large and small in- 

\ testines. P. 280. 
Genus and Species : 

CEsophagostomum columbianum. Hosts, sheep, goat. P. 
281. 

CE. venulosuni. Hosts, sheep, goat. P. 282. 

(E. radiatum. Host, cattle. P. 285. 

(E. subulatum. Host, hog. P. 287. 

Chabertia ovina. Host, sheep. P. 287. 



224 PARASITES OF THE DOIVIESTIC ANIMALS 

Stroiig.vlus eqiiinus. Host, equines. P. 288. 
St. edentatus. Host, equines. P. 289. 
St. vulgaris. Host, equines. P. 289. 
Cylicostonium tetracanthum. Host, equines. P. 289. 
Ankylostonia canina. Hosts, dog, cat. P. 291. 
Uncinaria stenocephala. Host, dog. P. 292. 
Bunostomuni trigonocephalum. Host, ruminants. P. 293. 
B. phlebotonium. Host, cattle. P. 293. 
Synganuis trachealis. Host, fowl. P. 293. 
Syn. bronchialis. Host, water fowl. P. 293. 
Family (f) Eustrongylida>. P. 296. 
Genus and Species : 

Dioctoplmne renale. Hosts, dog and other animals. P. 296. 
Family (g) Trichinellidse. P. 299. 
Genus and Species: 

Trichuris ovis. Host, ruminants. P. 299. 
T. crenatus. Host, hog. P. 299. 
T. depressiusculus. Host, dog. P. 300. 
Trichinella spiralis. Ho.sts, hog, rat, mouse, and other 
mammals. P. 301. 
Order 2. Acanthocephala. P. 306. 

Family (a) Gigantorhynchidte. P. 306. 
Genus and Species: 

Gigantorhynchus hirudinaceus. Host, hog, man. P. 306. 
Class B. .Annelida. Annulated worms. P. 307. 
Order I . Hirudinea. Leeches. P. 307. 
Family (a) Gnathobdellida-. P. 308. 
Genus and Species : 

Hirudo medicinahs. Medicinal leech. P. 309. 
Htemopis sanguisuga. Horse leech. P. 308. 

AVith slight omissions, the following descriptions of superfamilies 
and their subdi\-isions are transcriljcd from a work upon the nematode 
parasites of small mammals by Maurice C. Hall (1916). 

" E.^ojihagus consists of a chitinous tube which is embedded along 
the greater j^art of its length in a chain of single cells. The anterior 
portion of the body, occupied b_v the esophagus, usually very slender; 
the posterior portion, occupied by the intestine and reproductive 
organs, more or less swollen, or at least thicker than the anterior portion. 
Anus terminal oi- subterminal. Male with only one spicule or with no 
spicule. One testis. Female with one ovary. Vulva situated at the 
junction of the anterior and posterior portion of the body. Oviparous 
or ovoviviparous. In digestive tract or adnexa or in ui'inary bladder 
as adults. Life history usually simple. Larva of at least one intestinal 



COELHELMINTHES 225 

form penetrates to and encj'sts in the musculature of the host of the 
adult worm. 

Superfamily Trichinelloidea Hall, 1916. 

Type-family Trichinellidae Stiles and Crane, 1910. 

"Male without spicule. Female ovoviviparous; the spherical egg is 

surrounded with a dehcate membrane and is without a time eggshell. 

Worms in the intestine of the host animal. 

Subfamily Trichinellinae Ransom, 1911. 
Type-genus Trichinella RaiUiet, 1895. 
"Male with one spicule, or, exceptionally, with only a copulatory 
sheath. Eggs lemon-shaped, the apertures at each end closed with 
opercular plugs. Development, so far as known, direct and without 
intermediate host. Egg development often slow. Eggs with thick shell; 
do not hatch until swallowed by a suitable host. 

Subfamily Trichurinse, Ransom, 1911. 
Tj'pe-genus Trichuris, Roederer, 1761. 
"Mouth commonh' provided with two or three prominent or incon- 
spicuous lips which are often suppUed with papillae, but the mouth 
may be of variable shape and without lips. "Wlien three Hps are present 
one is median and dorsal, the others are submedian and are approximated 
in the ventral line. Buccal capsule is not present. Males are provided 
with one or two spicules, rarelj' with none. Female with two ovaries, 
oviparous, rarely, as in O.xyuris vivipara, viviparous. As a rule develop- 
ment is direct and without intermediate host; exceptionalh' (as in 
ascarids of fish) there is an intermediate host. 

Superfamily Ascaroidea, Railliet and Henry, 1915. 
"Mouth with three prominent lips suppKed with papillte, the dorsal 
lip being median and the two other submedian and approximated in 
the ventral line, or with three main lips and three relativeh' prominent 
and inconspicuous intermediate lips (interlabia) . Male usually with 
two spicules. Caudal extremity of female terminates conically and 
fairly abruptly. 

Type-famil}^ Ascaridse, Cobbold, 1864. 
Tj'pe-genus Ascaris, Linnjeus, 1758. 
"Mouth provided with two or three Ups or without lips and of va- 
riable shape. Esophagus cylindrical or club-shaped, often followed by 
a distinct bulb. Males with a preanal sucker, which may be limited 
by a chitinous ring or a dehcate cutaneous membrane, or formed bj' a 
simple longitudinal depression; this sucker is not present in Seuratum. 
Two spicules, one or both of which ma}^ tend to atrophy or show im- 
perfect chitinization, and with accessory piece present or absent. Vulva 
near middle of body. 

Family Heterakidse, Railhet and Heniy, 191-1. 
"Mouth with three well-defined lips; esophageal bulb present or 



226 PARASITES OF THE DOMESTIC ANIM-AXS 

absent; preanal sucker nearly circular and limited l)y a chitinous ring; 
spicules equal or uneciual. 

Subfamily Heterakinae, Railliet and Henry, 1912. 

Type-genus Heterakis, Dujardin, 1845. 

"Moutli with simple, usually inconspicuous lips. Male usually with 

one spicule, at times reduced, imperfectly chitinized or absent. Caudal 

extremity of female much elongated and sublobate. Vulva anterior. 

Eggs characteristically flattened on one side. 

Family Oxyurida, C'obbold, 1864. 

Sul)family Ox.\in"inae, Hall, 1916. 

Type-genus O.xyuris, Rudolphi, 1803. 

"Males with a well-developed caudal bursa supported bj' rays; in 

forms near the outer limit of the superfamily the bursa is occasionally 

very small and the I'ays atypical, or the bursa may be lacking altogether. 

Esophagus without posterior bulb. Mouth naked or with a buccal 

capsule and .six papillie, distinct or indistinct. Male usually with two- 

spicules and female usually with two ovaries. Oviparous or viviparous. 

Su])erfamily Strongyloidea, Weinland, 1858. 

"Buccal capsule present. Bursa highly developed, with a typical 

system of supporting rays consisting of one or two dorsal rays and two 

lateral I'ay .systems of six rays each. Male with two spicules and female 

with two ovaries. Vulva at times anterior to the middle of the body, 

but usually iiosferior of the middle. Oviparous, eggs segmenting when 

laid. Development, so far as known, direct. Embryo rhabditiform. 

In digestive, rarel.y in respiratoiy system. 

Type-family Strongylidse, Cobbold, 1864. 

"Buccal cajisule present. In digestive, occasionally in respiratory, 

system. Development direct, at times complex, involving cutaneous 

infection, nodular development or other embryonic or larval migration. 

Subfamily Strongylins, Railliet. 1893. 
Type-genus Strongylus, Mueller, 1780. 
"Simple mouth without a buccal capsule. Parasitic only in the di- 
gestive system. Development direct and simple, involving in all ca.ses 
known only the possibility of infection by ingestion. 

Family Trichostrongylida;, Railliet, 1915. 
"Body straight or curved, l)ut not regularly coiled in a spiral. Females 
with two ovaries. 

Subfamily Trichostrongylinse, Leiper, 1908. 
Type-genus Trichostrongjdus, Loess, 1905. 
"Buccal capsule present or absent. Bursa present or absent; when 
present, frequently atypical in stmcture and nmnber of rays. Ovip- 
arous, with eggs in variable stages of segmentation when oviposited, 
or viviparous. Embryo not rhabditiform. Usualh' in respirator}' and 
circulatoiy s.ystems, rarely in tligestive system. 



CCELHELMINTHES 227 

Family Metastroiigylidae, Leiper, 1908. 
"Buccal capsule absent. Male with two equal spicules and female 
with two ovaries. Eggs in varying stages of development when ovipos- 
ited. Embryo not rhabditiform. Parasitic in the respiratory and cir- 
culatory sj^stems. 

Subfamih^ Metastrongylinae, Leiper, 1908. 
Type-genus Metastrongylus, Molin, 1861. 
"Body usually very long and slender. Mouth with two lips or with- 
out lips and surrounded with circumoral papillae. Esophagus slender, 
without posterior bulb. Anus subterminal. Male with a single spicule 
or with two unequal spicules. Tail provided with papillae, usually 
curved spirally, and with bursal alse present or absent. Female larger 
than male. Vulva present, or, less often, absent in gravid females; 
when present, usually anterior to the middle of the body or near the 
middle, rarely near posterior extremity. Oviparous, ovoviviparous, 
or viviparous. Development in many cases, perhaps in all, requires 
an intermediate host. 

Superfamily Filarioidea, Weinland, 1858. 
"Body long and filiform. Mouth without lips. Male with two 
spicules, usually quite dissimilar. Vulva near the anterior extremity of 
the body. Adults subcutaneous, in blood, or on serous surfaces. 

Type-family Filariidse, Glaus, 1885. 
"Vulva anterior, near mouth. Spicules quite dissimilar. Inter- 
mediate stages, so far as known, occur in blood-sucking arthropoda. 

Subfamily Filariinae, Stiles, 1907. 

Type-genus Filaria, Mueller, 1787. 

"Mouth with two lips; or without lips in forms where vulva is near 

posterior extremity of body. Male with posterior extremity of body 

commonly expanded and alate. Female with vulva usually in middle 

portion of body, exceptionally near posterior extremity. 

Family Spiruridae, CErly, 1885. 
Type-genus Spirura, E. Blanchard, 1849. 
"Body long and filiform. Anterior portion of bodj' ornamented with 
cuticular bosses. In the median lines, immediately behind the mouth, 
are two semilunar depressions simulating suckers. The vulva is sit- 
uated a short distance anterior of the anus. 

Sulifamily Gongyloneminae, Hall, 1916. 
Tj'pe-genus Gongylonema, IMolin, 1857. 
"Females with two uteri and with vulva in the middle portion of 
the body, not close to anterior or posterior extremities. Pharj-nx with- 
out cuticular raj's or spirals. 

Subfamily Spirurimp, Railliet, 1915. 

Tj'pe-genus Spirura, E. Blanchard, 1S49. 

"Mouth with two lips leading hito a pharynx which is .strengthened 



228 PARASITES OF THE DOIMESTIC ANIMALS 

by cuticular ridges in the form of rings or spirals. Spicules unequal, 
the longer several tunes the length of the shorter. Four pairs of preanal 
papillae. Eggs containing embryos when oviposited. 

Subfamily Arduenninae, Railliet and Henry, 1911. 
Tj'pe-genus Arduenna, Railliet and Henry, 1911. 



CHAPTER XIX 
NEMATODA. FAMILY I. ASCARIDiE 

The Large Koundwoems of the Intestine 

Nematoda (p. 217). The nematodes of this family have the body" 
relatively thiclc (Fig. 125). The mouth is commonly provided with 
three lips which may be prominent or inconspicuous and often bear 
papilla3. When three Hps are present one is dorsal, the other two sub- 
median, touching on the ventral median line (Fig. 121). The males 
are somewhat smaller than the females and usually have the caudal 
extremity curved ventrally in the form of a hook. There may be one 
spicule or two. The females have two ovaries and they are oviparous. 
So far as known, development in all which are parasitic in warm-blooded 
animals is without intermediate host and infection is direct. 

All of the ascarids live as parasites in the intestines of their hosts, 
though they may be found in other organs and in the bodj^ cavities 
reached by their migrations. They hve free in the in- 
testinal contents, obtaining their sustenance by absorp- 
tion of the partly digested nutriment of their host 
through their simple alimentary tube. 

Investigations as to Life History. — Investigations 
by Capt. F. H. Stewart (F. H. Stewart On the Life 
History of Ascaris lumbricoides, British Medical Jour- 
nal, 1916, Vol. 2, No. 2896) have brought results of 
great importance bearing upon the hfe history of Ascaris ^i?- 121.— Dor- 
lumbricoides and closety related forms. In these experi- ^? ^extremity* of 
ments Stewart found that if rats or mice were fed ascarid, showing 
Ascaris eggs, the eggs hatched in the alimentary tract superior median 
and the embryos migrated to the liver, spleen, and lungs, lateral lips. 
During these migrations they passed through certain 
developmental changes, and many of them finally again reached the 
alimentary tract by way of the lungs, trachea, and esophagus. Within 
the alimentary tract they did not continue their development and were 
soon expelled with the feces, so that rats and mice surviving the pneu- 
monia commonly caused bj' the invasion of the lungs became free of 
the parasites as early as the sixteenth day after infection. 

From these findmgs Stewart concluded that in infection with Ascaris 
lumbricoides it is necessary in the life cj'cle for the eggs to be swallowed 
by rats or mice, and that the embryos hatching from the eggs undergo 




230 PARASITES OF THE DOMESTIC ANIMALS 

certain migrations and changes of development, after which they may 
be carried in the feces or saliva of the rats or mice to food or other 
materials which may be ingested by human beings or pigs, thus ulti- 
mately reaching their final host. 

This conclusion is contrary to the opinion usually accepted that 
Ascaris infects man or the pig directly through the ingestion of the eggs 
of the parasite. In a preliminary note upon the life history of Ascaris 
lumbricoides and related forms Ransom and Foster, of the Zoological 
Division of the Bureau of Aninuil Industry, state that in a repetition 
of Stewart's expeiiinents in feeding rats and mice with Ascaris eggs 
they obtained results agreeing very closely with those which he had 
recorded, also that further investigations have shown that guinea pigs 
as well as rats and mice may be similarly infected by feeding Ascaris 
eggs. Their negative or uncertain results from attempts to infect pigs 
with Ascai'is by feeding the eggs agreed with the experience of Stewart 
and other investigators, nevertheless they did not feel justified in accept- 
ing these results as evidence against the hypothesis of a direct develop- 
ment without an intermediate host. They note that Epstein in care- 
fully controlled experiments with feeding eggs of Ascaris lumbricoides 
used very young sulijects and that the positive results which he obtained 
can scarcely be explained upon any other assumption than that a direct 
development of the parasites occurred following feeding of the eggs. 
The failures of others to infect adult human beings and the unsuccessful 
attempts to infect pigs several months old in the same way are considered 
as suggesting the i)ossil)ility that age is an important factor influencing 
the susceptibility of human beings and pigs to infection with Ascaris. 
In .sujiport of this, and in agreeiuent with the migration of larvae which 
occurs in rats and mice, they cite an instance of a pig about six weeks 
old which, dying from unknown causes, revealed on examination an 
Ascaris larva in a fragment of lung and numerous imiuature ascarids 
in the intestine, the largest about two inches long. 

In order to test the possibility of infecting very young pigs these 
investigators used two young pigs from a sow which was found by fecal 
examination to be free from egg-producing ascarids. At the age of 
about two we(>ks one of these pigs was given a large immber of Ascaris 
eggs containing motile-vermiform emliryos. One week after feeding 
the eggs this pig died; the other pig continued in good health. "Exam- 
ination of the dead pig," the authors state, "revealed a pneumonia, 
with numerous petechial hemorrhages in the lung tissue. Numerous 
ascarid larvae, vaiying in length from 0.7 to 1.2 mm. in length, were 
found iji the lungs, trachea, and pharynx; none in the liver, spleen, 
esophagus, small intestine, or large intestine." As to conclusions the 
authors are further quoted as follows: 

"Stewart's very important discoveries concerning the behavior of 



ASCARID-E 231 

Ascaris larvae in rats and mice, the various contributions of other in- 
vestigators toward the solution of the problem of the life history of 
Ascaris lumhricoides and related parasites, and our own experiences, 
appear to justify certain conclusions, some of which in anticipation of a 
more extended statement in a future paper, may be briefly given as 
follows : 

"The development of Ascaris lumhricoides and closely related forms 
is direct, and no intermediate host is required. 

"The eggs, when swallowed, hatch out in the alimentarj^ tract; 
the embryos, however, do not at once settle down in the intestme, but 
migrate to various other organs, including the liver, spleen, and lungs. 

"Within a week, in the case of the pig Ascaris, the migrating larvae 
may be found m the lungs and have meanwhile undergone considerable 
development and growth. 

"From the lungs the larvae migrate up the trachea and into the 
esophagus by way of the pharynx, and this migration up the trachea 
may already become established in pigs, as well as in artificially infected 
rats and mice, as earlj' as a week after infection. 

"Upon reaching the alimentaiy tract a second time after their passage 
through the lungs, the larvae, if in a suitable host, presumably settle 
down in the intestine and complete their development to maturity; 
if in an unsuitable host, such as rats and mice, they soon pass out of 
the bod.y in the feces. 

"Heavy invasions of the lungs by the larvae of Ascaris produce a 
serious pneumonia which is frequently fatal in rats and mice and ap- 
parently caused the death of a young pig one week after it had been 
fed with numerous Ascarid eggs. 

"It is not improbable that ascarids are frequently responsible for 
lung troubles in children, pigs, and other young animals. The fact 
that the larvae invade the lungs as well as other organs beyond the 
alimentarj'- tract and can cause a serious or even fatal pneumonia in- 
dicates that these parasites are endowed with greater capacity for harm 
than has heretofore been supposed. 

"Age is a highlj- important factor in determining susceptibility to 
infection with Ascaris, and susceptibility to infection greatly decreases 
as the host animal becomes older. This, of course, is in harmony with 
the wellrknown fact that it is particularly children and }'Oung pigs 
among which infestation with Ascaris is common, and that Ascaris is 
relatively of rare occiu-rence in adulfhuman beings and in old hogs." 

ASCARIASIS 

Ascariasis occurs most frequently in 3'oung animals, those matured 
rarelj^ harboring the worms in such numbers as to bring about sj'mptoms 



232 PARASITES OF THE DOIHESTIC ANIAIALS 

by which the condition can be recognized. Where there is a heavy in- 
festation thcj- cause injury by their irritation to the intestinal mucosa. 
In such cases thej' may become massed and constitute an obstruction 
to the intestinal lumen sufficient to cause stasis of the contents and de- 
generative changes in the intestinal walls. 

The ascarids are active worms, and have a tendency to wander to 
unusual locations; one or two maj' find lodgment in accessoiy organs of 
the intestines by waj* of their ducts and, by the consequent continuous 
irritation, bring about results of a serious nature. \^erminous fistulae 
may be thus established, or there may be abscess formation with dis- 
charge of pus into the peritoneal cavity, followed by peritonitis. In 
dogs and cats especially', the worms when numerous often pass to the 
stomach in considerable nmubers, setting up more or less gastric dis- 
turbance and consequent vomiting, the expelled material generally 
containing from one to several worms. 

Certain foreign investigators, having demonstrated the presence of 
blood in ascarids, have concluded from this that these worms are blood 
suckers. Hall, in an article upon the parasites of the dog in Michigan 
(Journal of the Ajuerican Veterinaiy Medical Association, June, 1917), 
states that an ascarid which he collected from the feces of a dog showed 
a pronounced red color in the intestine, evidently due to blood. As 
post-mortem examination of the dog the same day revealed a severe 
hemorrhagic enteritis, he concludes that this was evidently the explana- 
tion for the blood in the intestine of the ascarid. The conditions found 
in this case suggest the possibility of similar conditions in cases regarded 
as evidence that these worms are blood suckers, — a conclusion that cer- 
tainlj- has no support in the stmcture of the ascarid's mouth. 

There seem.s reason to doubt that ascarids feed upon epithelial cells, 
as stated by some authors. Their simple intestinal tube is restrictively 
modified to the primary function of absorption of nutriment already 
made in a certain state of solution by the digestive juices of the host, 
and it is unlikel>' that such digestive powers as are retained by the 
parasites would be adapted to a diet of epithelial cells. In view of the 
fact that free epithelial cells and tlieir d6bris are contained in the alimen- 
tary contents of the host, it follows that .such material would be in- 
gested along with the alimentary matter by the worms and would be 
found in their intestinal contents. 

Aside from the mechanical injury caused by the ascarids, there are 
to be considered the effects of toxic jiroducts elaborated by their bodies. 
These may be practically nil or considerable according to the character 
and degree of the infestation. The loss of condition in heavy invasions 
can proliably be attributed to the systemic effect of these poisons com- 
bined with that of the catarrhal enteritis. It seems reasonable to con- 
clude that the deprivation of nutriment, which has been appropriated 



ASCARID^ 233 

by the horde of parasites in the alimentary canal, is also a morbid factor. 
Manifestations of the toxemia are often of a nervous character; there 
is hyperreflex irritability, and convulsions are a not infrequent accom- 
paniment. 

In general, it may be said of the ascarids that, while they often in- 
habit the intestines without perceptible indications of then invasion 
other than their occasional expulsion with the feces, their presence con- 
stitutes a condition calling for treatment. They should be expelled by 
the administration of a vermifuge, in most cases followed by a purgative, 
and their bodies collected and burned. Not only should the treatment 
be carried out for considerations pertaining to the health of the host, 
but to prevent the spreading about of the worms with their eggs and 
embryos to infest other animals. 

ASCARIDJE OF THE HORSE 

One species of ascarid inhabits the intestine of the horse, ass, and mule. 

Ascaris equi (A. megalocephala, A. equorum). Ascaridse (p. 229). — 
This is the largest species of the family. The bodj' is j^ellowish white, 
about the thickness of a lead pencil, and somewhat rigid. The head 
is distinct and bears three lips. The caudal extremity of the male is 
bordered laterally by two small membranous wings, and ventrally on 
each side there are 80-100 papillse. The female is considerably longer 
and thicker than the male. The vulva is situated toward the anterior 
quarter of the body. 

Length of female: 15-30 cm. (6-12 inches), or it may be somewhat 
longer. 

Eggs globular, 90-100 microns in diameter. 

The species is found only in Equidse, and hves in the small intestine, 
occasionally found in other organs by migration. 

Occurrence and Symptoms. — The large ascarid is verj^ common in 
the small intestine of the hor.se. Unless numerous, they do not, as a 
rule, perceptibly affect the health of then host, often the only e^-idence 
of their presence being the voiding of one or more of the worms with 
the feces. Young animals do not bear the parasitism so well, and in 
moderate to heavj^ infestations are likely to manifest serious disturb- 
ances of a local and sj^stemic character. 

As a result of the nritation to the mucosa there is a chronic intestinal 
catarrh, and this may be accompanied bj^ a diarrhea which is persistent, 
or alternating with a hard dry feces covered with sUmy mucous material. 
Colic is a not infrequent sjnnptom, and there maj' be intervals of more 
or less tympany. The worms, when massed in large numl^ers, are 
capable of bringing about an obstiaiction with all that follows such a 
condition, possibly involving intussusception and even rupture. 



234 PARASITES OF THE DOMESTIC ANI]VL4LS 

Young animals, as a result of aggravated aseariasis, lose condition 
and there is arrest in their development. Due largely to the accinnula- 
tion of gas, they are likely to become more or less pot-bellied, the activity 
of the skin is reduced, and the coat takes on a dry, harsh, and erect 
appearance. The alertness and inclination to play, natural to foals and 
young hor.ses, is lost, and the animals may stand about looking more or 
less dejected. 

Nervous distmbances are occasionally exhibited bj' vertigo or, 
rarely, by epileptiform or tetanic symptoms. They may be due to reflex 
irritation or to toxic products from the bodies of living worms, to which 
is added toxins from the bodies of worms which are dead and decompos- 
ing. 

Etiology. — Infection occurs by the introduction of eggs and embryos 
into the alimentary canal with food and water. Development takes 
place after the eggs have left the bodj^ of the host and is favored by 
factors of warmth and moisture, such as is supplied by moist earth and 
a temperature of about 37° C. (98° F.). While segmentation will not 
proceed under low temperature conditions, the eggs will retain their 
fertility in unfavoi-able surroundings for a comparativel.v long period 
and will develop upon reaching a favorable environment. Embryos 
within the eggs ajipear to possess considerable resistance, since they 
have been observed to retain their vitality in dried horse manure for 
six montlis. It is prol)able that infection is by eggs, and that few em- 
bryos are released until the intestinal contents of the equine host is 
reached. 

Control. — Considering the persistent vitality of the eggs and em- 
bryos, it is especially important as a prophylactic measure that as manj' 
as possible of the expelled worms be collected and burned. If thej^ are 
permitted to find their way to the manure pile or to be scattered about, 
some of the myriads of eggs contained in their bodies will meet with 
conditions favorable to their development an<l infect other horses. 
Precaution should be taken that the drinking water for horses does not 
receive contamination from collected manure, and that it be as pure and 
free from smface drainage as possible. 

Treatment. — Treatment should be preceded by the withholding of 
all bulk\- food for twenty-four to forty-eight hours. During this time 
the animal .should bo at rest and may be given bran mashes, to which a 
moderate amount of grain may be added during the first twenty-four 
hours if the preparation is to be for the longer period. 

While the pr(>liminary fasting of the host for a day or two probably 
will not sufficiently "starve" the parasites to be of any value as an aid 
in their expulsion, it permits the removal of the bulky portion of the 
intestinal contents and prepares for a diffuse action of the anthelmintic 
which otherwise would not l)e possible. 



ASCARID^ 235 

Following the period of fasting, give two to four ounces of oil of tur- 
pentine and one dram of oleoresin of aspidiiuii, in a pint of linseed oil. 
If necessary, follow twelve hours later with an additional pint or two of 
linseed oil. 

Tartar emetic in two to three dram doses, repeated once at an interval 
of twelve hours, is also an effectual expellant. This is best administered 
with linseed meal which may be stirred into a small bran mash. 

These doses are for aged horses of average size, and are to be modified 
according to age and somewhat as to weight. 

The vermifuge is in most cases to be followed twelve to twenty-four 
hours later by a purge, preferably oleaginous, but this should not be 
given if there is diarrhea, and maj'' not be necessary if the animals are 
upon grass. 

Sulphate of iron and arsenic are remedies which have also been recom- 
mended. If arsenic is used, it should be given in the form of powdered 
arsenous acid in inci'easing doses for about two weeks. 

Family II. Oxyuridae. Nematoda (p. 217). — This family is consid- 
ered by many authors as belonging with the Ascaridse. Conspicuous 
characteristics of the group are the curved anterior portion of the body 
and the elongated and attenuated caudal extremity of the female. The 
males usually have but one spicule, and this may be reduced and mi- 
perfectly developed. The wilva of the female is anterior. 

Oxyuris equi (O. curvula, O. mastigodes). Oxyuridse (p. 235). — 
The bodj^ is generally white, somewhat thickened, and curved. The 
mouth is provided with three lips. The male is much smaller than the 
female, and has an obtuse caudal extremity which bears several papillae, 
the largest of which sustains a caudal bursa. There is but one spicule 
and this is straight and slender. In the female the anterior portion of 
the body is thickened and curved, while the posterior portion is at- 
tenuated to a point. The vulva is about 8-10 mm. (3/8 of an inch) from 
the mouth. The body maj^ have its posterior attenuated portion of 
variable length (Fig. 122) ; in some individuals this is very much pro- 
longed and filamentous. This difference has led some authors to 
describe two species of Oxyuris of the horse — 0. curvula and 0. masti- 
godes, the latter including those with the extended caudal extremity. 
Railliet has demonstrated that forms exist possessing all intermediate 
gradations between those with very short and those with very long tail 
extremities, and that there is not, therefore, a difference of true specific 
character. 

Length of female, 4-1.5 cm. (1 5/8-6 inches) ; male, about 1 cm. (3/8 of 
an inch). 

Eggs oval and operculated; 85-95 microns long, 40-45 microns wide. 

The species inhabits all of the large intestine of the horse, ass, and 
mule. 



23(5 PARASITES OF THE DOMESTIC ANBL\LS 

Occurrence. — Oxyuris cqui is a common inhabitant of the large intes- 
tine of the horse. The condition produced by these worms is usually 
referred to as oxAiiriasis, and they are conmionly known as seat-worms 
or pin-worms. Often they are observed projecting from the margin of 
the anus to which thej' adhere while depositing their eggs. By means 
of a sticky substance the eggs attach about the skin of the anus and 
perineum and develop embr3-os within two to three days. Later the 
sul^.stance by which they are fixed to the skin dries and the eggs drop 




Fig. 122. — 0.xyuris equi, showing varying lengths of posterior 
attenuated portion. 

to the grovuid where, through scattered manure, they contanunate the 
jiasturage, or, if the animal is in the stal)le, the feed may be contam- 
inated in the same manner. 

The eggs are pi'ovidcd at one end with a sort of opeiTulmn which, on 
reaching the stomach, is digested awaj'. The released embryos are then 
carried with the alimentary material to the large intestine where they 
reach maturity. 

Effect. — The offense of the oxyurids is mainly one of unsighthness. 
The}' produce itching about the anus which maj' become intense, causing 
the animal to I'ul) the parts and thus bring about a denudation of the 



ASCARIDiE 237 

tail and sldn. The tail is frequently agitated, and annoj-ing habits of 
"switching" and "line-hugging" maj' have origin from this source. 

In aggravated cases there may be loss of flesh due to the constant 
irritation to which the animal is subjected. The anus becomes swollen, 
flacid, and, on defecation, the mucous membrane is noticed to be a deep 
red. 

The condition is readily diagnosed in observing the protrudmg or ex- 
pelled worms. The sticky yellowish-colored deposit about the anus and 
perineimi, together with denudation of the skin and base of the tail 
by rubbing, mdicates the presence of the worms. 

Treatment. — Treatment is mainly per rectum. Previous to the ad- 
ministration of vermifuge enemata the bowel should be emptied by an 
injection of glycerm and water or of warm soapy water. As an expellant, 
either of the following may be used: (1) Infusion of quassia, one to two 
quarts; (2) infusion of tobacco, one ounce to one quart of water; (3) 
vinegar in soapy water; (4) one quart of a one per cent, solution of 
lysol; (5) one to two oimces of oil of turpentine shaken up in a quart of 
lime water and linseed oil; (6) mercurial ointment repeatedl}^ applied 
to the borders of the anal orifice is also of service. The injections are 
best given through a rubber siphon. 

As developing worms from ingested eggs may be in the intestines too 
far forward to be acted upon by the enemata, it is well to supplement 
this treatment with the administration of a vermifuge as recommended 
for the large ascarids of the small intestine. 

Treatment is to be repeated at intervals of four to six days until 
indications of the presence of the worms have disappeared. 

The adhering deposit about the rectum and perineum should be 
regularly removed and so disposed of that the contained eggs cannot 
reinfect. 

Ascarids of the Dog and Cat 

One species of ascarid is common in the dog and cat, although some 
authors recognize two — Belascaris marginata of the dog, and B. mystax 
of the cat. Other than being a little smaller, the ascarid of the cat 
scarcely differs from that of the dog, and at the present tune the ma- 
jority of hehuinthologists consider the difference as one of variety onh^ 

A much less common species infesting dogs in this country is Tox- 
ascaris limbata. 

Belascaris marginata (Ascaris marginata, A. mystax, Belascaris 
mystax, B. cati). Ascarid^e (p. 229). — The body is white, or reddish 
white. The head is usually curved and is provided on each side with a 
membranous wing, giving the appearance of an arrow-head (Fig. 123). 
On the curved tail of the male there are two small membranous 
lateral wings and twenty-six papillae on each side. The \'Tilva of the 



-238 PARASITES OF THE DOMESTIC ANIMALS 

female is situated toward the anterior quarter of the l)ody. The tail 
is obtuse. 

Length of female, 9-14 cm. (3 1/2-5 1/2 inches); male, 5-10 cm. (2-4 
inches). 

Eggs globular, 75-80 microns in diameter. 

Infests the small intestine. 




Fio. 123. — Belascaris margiiiata: A, head, enlarged; 
male; C. female, natural size. 

Toxascaris limbata (Toxascaris marginata). Ascaridae (p. 229). — 
The body is firm and whitish or pale red in color. The cephalic wings 
aic long, narrow, and somewhat lanceolate. The spicules of the male 
are not (juite equal. 

Length of female, 6.5-10 em. (2 1/2-4 inches) ; male, 4-6 cm. (1 1/2- 
2 3/8 inches). 

The eggs are 75 to 85 microns in diameter. 

Parasitic in the in(<'stines of the dog. 

Occurrence in the Dog. — Bclascariti manjinata is most often found 
in young dogs of thiee to four months. It is probable that about thirtj^ 
per cent, of all puppies harbor the worms in more or less numbers in 



ASCARID^ 239 

their small intestine. Thej' frequently enter the stomach and cause 
vomiting, the expelled material often containing several worms. Other- 
wise the symptoms are much like those caused by the presence of tape- 
worms. There is emaciation, enlarged abdomen, and irregular appetite. 
There may be diarrhea or constipation, and, finally, epileptiform or 
rabiform seizures. By massing in the small intestine, they may induce 
invagination and fatal obstruction to the alimentaiy matter. 

Necropsies upon dogs which have died from ascariasis reveal the 
lesions of an intense hemorrhagic enteritis, with txmiified mucosa, show- 
ing small ulcerative points and involvement of the submucous tunics. 

Treatment. — (1) Powdered areca nut, two grains to each pound of 
body-weight, may be given shaken up in a little milk. (2) Santonin is 
one of the most frequently used remedies. The dosage should be care- 
fully graded, giving one-eighth of a grain per pound of body-weight, the 
dose in no case to exceed three grains. It may be administered sus- 
pended in milk or combined with one-fourth to two grains of calomel, 
made into a pill. (3) Fifteen minims to one dram of oleoresin of as- 
pidium, singly or combined with a grain of areca nut, per pound of body- 
weight, may be given in capsule. (4) Benzene, in fifteen drop to one 
dram doses in oil, has been recommended. 

The anthelmintic should be administered in the morning after a 
twelve hours' fast. If the bowels are not already freely active, it is 
well to follow the remedy a few hours later with a purgative of castor 
oil or synip of buckthorn. Care should be taken in the administration 
of these drugs to toy puppies. Santonin, especially, should not be given 
until they are at least eight weeks old; under that age, a simple laxative 
will often bring away quite a number of the woi-ms. 

If vomiting occurs after giving the medicine, allow an interval of 
two or three days before repeating; then precede by a stomach sedative 
of bismuth or a small dose of cocaine. 

Occurrence in the Cat. — Ascariasis of the cat does not sufficiently 
differ from that of the dog to merit a special description. As in the dog, 
the worms are more likely to infest j^oung aninaals, though cats seem 
to bear the invasion better. 

Remedies recommended for the dog ^\^ll serve as well for the cat, 
though the peculiar intolerance of these animals should be taken into 
consideration in the selection and dosage. (1) Cusso, fifteen to thirty 
grains, is relatively safe, but is likely to cause vomiting. (2) Oleoresin 
of aspidium, minims fifteen to twenty, may be given in milk. 

ASCARID^ OF THE HoG AND ShEEP 

Ascaris lumbricoides (A. suis, A. suum, A. ovis). Fig. 125. 

Ascaridffi (p. 229). — The head has three strong lips, the lateral sides of 



240 



PARASITES OF THE DOMESTIC ANIMALS 




Fui. 124. -Egg of 
Ascaris himbricoides, 
with shell and albu- 
minous fnvelope 
(copied from Braun's 
"Animal Parasites of 
Man"). 



which are generally 
denticulate. The body 
is white, firm, and elas- 
tic. The males have 
two spicules and numer- 
ous papilla anterior and 
(losterior to the anus. 
The vulva of the female 
is situated toward the 
anterior third of the 
bod J'. 

Length of female, 20- 
25 cm. (8-10 inches); 
male, 15-17 cm. (6-6 3/4 
inches) . 

Eggs, oval, 60-75 microns long by 40-58 
microns wide. The shell is mammillatcd. 

In its adult state this worm hves in the 
intestines of the hog and sheep, and also of 
man. 

The ascarid of the hog and sheep and 
that of man so closely resemble each other 
that a number of authors now consider 
them as one species; others distinguish a 
specific difference, claiming that the ascarid 
of the ])ig differs from the himian ascarid 
in l)eing thinner, having the longitudinal 
striffi closer, spicules less sharp, and ova 
smaller. It would seem, however, that such 
slight differences should be regarded as of 
no more than varietal importance. 

Hea\y invasions of these worms in the 
intestines of hogs bring about the con- 
ditions such as have already been described 
in aggravated intestinal helminthiasis. In 
young pigs especially, there is general un- 
thrift, and emaciation may become quite 
advanced. There is usually a cough, and 
this is likely to be accompanied b}' occa- 
sional vomiting. The jiig shows a pecu- 
liar restlessness, wandering about without 
apparent motive and emitting cries indica- 
tive of colicky pains. The lumen of the 
intestines mav l)e obstructed bv the 




Fig. 12.5. — Ascaris lumbri- 
coides, male at right, female at 
left, natural size. 



ASCARID.E 241 

worms in mass with the usual sequence of localized inflammatory 
changes. 

Invasion of the bile duct of pigs with these ascarids is of frequent 
occurrence and maj^ often bring about a fatal result. Autopsies at the 
Pennsylvania State Laboratories upon pigs dead from this parasitism 
have in some cases revealed the common bile duct literal!}' packed and 
occluded with the worms. 

Treatment. — Treatment is mainly prophylactic. Thorough clean- 
ing up, burning of litter, and a liberal application of disinfectants is 
essential, and the source of water supply and drainage should be looked 
to. Infested pigs should be isolated and precautions taken against 
reinfection. 

Medicine is best administered in milk, or other semi-fluid media, fed 
to the pigs as a whole, the dosing of individual pigs being a somewhat 
discouraging task. It is better to separate the pigs for this purpose into 
groups of not more than ten of nearly equal size, otherwise the largest 
and most aggressive will get more than their portion. 

As a vermifuge, pulverized areca nut may be used, the dose being 
approximately one grain to each pound of body-weight. This should 
be followed by a purgative, preferably saline, the dose graded according 
to size of pigs, and administered as above. Benzene, in one to three 
dram doses mixed with the food, has been recommended as effective. 

When individual treatment of young pigs is resorted to, one to five 
grains of calomel, given in milk and followed by castor oil, will in many 
cases be sufficient to dislodge the worms. For older pigs it is better to 
follow the calomel with a saline evacuant. 

Ascariasis of Sheep. — Ascarids are rarely found in sheep. In the 
Bureau of Animal Industrj^ Collection there are specimens of ascarids 
obtained from sheep at Blairsville, Pa., Brookings, South Dakota, and 
Bethesda, Md. (Bulletin 127, 1911.) 

ASCARU)^ OF THE Ox 

Ascaris vitulorum. Ascaridse (p. 229). — The head is small and has 
three lips which are somewhat enlarged at the base. The body is white 
or may be reddish white. The caudal extremity of the male has two 
rows of papillae, 10-15 in each; these are lateral and pre-anal. The \ailva 
of the female is situated toward the anterior sixth of the body. 

Length of female, 22-30 cm. (8 1/2-11 3/4 inches) ; male, 15-20 cm. (6- 
7 3/4 inches). 

Eggs, 75-80 microns in diameter. 

Lives in the intestine of calves; rare in adult cattle. 

This worm is most frequently met with in parts of Southern Europe, 
where it is found in rather large numbers in the small intestine of cah'cs 
slaughtered for veal. 



242 



PARASITES OF THE DOMESTIC ANIMALS 



Heterakiasis of Chickens 

Family III. Heterakidae. Xematoda (p. 217).— This family, like 
the OxyuniUp, is j^laccd hy some authors with the Ascaridse. The 
type-genus is Heterakis, of which two species infesting chickens are to 
be described. 

1. Heterakis perspicillum (H. infiexa). Fig. 126. Heterakida; 
(p. 242).— The niuuth has thiee lips (jf unequal size, the dorsal lip the 
largest. The bo(l\- is yellowish white. The caudal extremity of the 




Flu. 126. — Heterakis per.spifillum: a, female; b, male; 
c, Heterakis vesicularis. All natural size. 

male terminates obliquely, and is provided on each side with a mem- 
branou,s wing and ten papillae. The two spicules are nearly equal. 
On the ventral surface anterior to the anus there is a rounded sucker. 
The caudal extremity of the female is .straight, conical, and terminates 
in a point. The vulva is located in the anterior part of the body. 

Length of female, 6-12 cm. (2 1/2-4 3/8 inches) ; male, 3-8 cm!^ (1 1/4- 
3 1/8 inches). 

Eggs, elliptical, 7o-80 microns in length by 4o-50 microns in width. 

The species is conunon in the small intestine of the chicken, turkey, 
and guinea fowl. 

2. Heterakis vesicularis (H. papillosa). Fig. 126. Heterakidae 
(p. 242). — The mouth has three small lips of equal size. The body is 



ASCARIDiE 243 

white and attenuated at its two extremities. The caudal extreniit\' of 
the male is straight, with lateral wings, and twelve papillae. The spicules 
are unequal. The caudal extremity of the female is very slender. The 
vulva is posterior to the middle of the body. 

Length of female, 10-15 mm. (3/8-5/8 of an inch); male, 7-13 mm. 
(5/16-1/2 inch). 

Eggs, elliptical, 63-71 microns in length by 38^8 microns in width. 

This species — much smaller than the preceding — is also common, 
and lives, in the cecum of the chicken, turkey, guinea fowl, pheasant, 
pea-fowl, duck, and goose. 

Symptoms. — Heterakiasis of chickens is usually caused by Heter- 
akis perapicillum. In general, the presence of the worms is indicated 
by dullness and an indisposition to move about. Though the appetite 
may be preserved, there is more or less emaciation, the feathers become 
erect and lusterless, and the wings droop. If the condition is aggravated 
the symptoms progress, diarrhea sets in, the appetite dwindles, the 
comb becomes pale, and the creature, with eyes half closed, remains 
huddled up and unmovable until death comes to its relief. 

In such cases necropsy will reveal the lesions of a subacute enteritis, 
and frequently the presence of numerous tapeworms as well as round- 
worms. 

Intestinal helminthiasis in fowls is often an accompaniment to diseases 
presenting somewhat similar symptoms, therefore care should be taken 
that a coincidence does not mislead, and that such causes of high mortal- 
ity as fowl-cholera be not overlooked. 

Treatment. — Sick birds should be isolated in clean bright quarters 
and their droppings frequentl}' removed and destroj''ed. As medicinal 
treatment, probablj^ areca nut is most effectual. This may be given to 
full-grown birds in doses of eighteen to twenty-four grains, administered 
in bolus made up with linseed meal or bread. Calomel, one to two grains, 
given in the same manner, has also been recommended. 

Essentially, thorough cleaning up and disinfection are necessary' to 
the successful eradication of the parasites. 



CHAPTER XX 
NEMATODA. FAMILY IV. FILARIID.E 

The Thread-like Worms 

Nematoda (p. 217). — The nematodes of this family have the bodj' 
long and filiform (Figs. 127 and 129). The shape of the mouth varies; 
it ma_v be provided with lips or it may be surrounded with papillae. 
The esophagus is slender, without posterior bulb. The males maj' have 
one spicule or two unequal spicules, and the tail is generally spirally 
rolled. The females have two ovaries; vulva usuallj' anterior to the 
middle of the body. The embryonal development is usuallj' within the 
body of the female. 

Parasitism. — The filariffi live as parasites chiefly in serous cavities 
of the body, blood and lymph channels, and in the submucous and sub- 
cutaneous connective tissues. They maj' be found in most an}' part of 
the body, but do not commonly inhabit the lumen of the alimentary 
canal. 

The parasitism of the filarise produces a condition in their hosts known 
as filariasis. 

FlLARIID/E OF THE HoRSE 

1. Setaria labiato-papillosa (Filaria equina). Fig. 127. Filariidse 
(p. 244). — -The body is long, white, filiform, and attenuated at both 
ends. The intogmnent has fine transverse striations. The mouth is 
small, circular, and i:)rovided with a chitinous ring, the border of which 
is divided by four salient papilla;. Outside of this on each side are two 
small jjapillae in the form of small spines. The tail of the male is rolled 
up s])irally and presents on each side four preanal and four or five 
postanal papilla;. There are two spicules. The tail of the female is 
. slightl\- spiral and is terminated by a papilla. The x'lilva is situated 
near the anterior extremit.y. 

Length of female, 9-12 cm. (3 1/2-4 .3/4 inches); male, 6-8 cm. 
(2 3/8-3 1/8 inches). 

Newly hatched embn'os are about 280 microns long by 7 microns in 
breadth. The embryonic development is within the body of the female. 

Occurrence. — This species is most often met with in the peritoneal 
cavity — more rarel>' in the pleural cavity of the horse, ass, and mule. 
The worms are especially fitted for migrations by their slender and 
attenuated bodies, and, from their location in serous cavities, may pass 



FILARIID^ 



245 



to the subperitoneal and subpleural connective tissues or to the mus- 
cular septa, scrotmn, or other parts of the body. The small filarise 
occasionally found in the anterior chamber of the eye are considered 
by most authors to belong to this species. 

Effect. — Unless present in exceptionally large numbers, these worms 
do not produce serious disturbance. Their presence in the eye may 
cause inflammation with bulging and opacity of the 
cornea for the relief of wliich operative measures must 
be resorted to. 

Nothing definite is known as to the evolution of 
this nematode ; the fact that the embryos have been 
observed in the blood of the horse, points to the 
probability that they pass to the body of a blood- 
sucking insect. 

2. Habronema megastoma (Spiroptera megas- 
toma). Filariidae (p. 244). — This is a small nematode 
with whitish colored body attenuated at the extremi- 
ties. The cephaUc portion is separated from the 
remainder of the body by a constriction, and is pro- 
vided with four chitinous lips. The mouth is con- 
tinued by an infundibuliform pharynx. The caudal 
extremity of the male is rolled and bears two lateral 
wings,each sustained by four preanal and one pos- 
tanal papillae. There are two spicules. The tail of 
the female is straight and obtuse; vulva situated to- 
ward anterior third of the body. 

Length of female, 10-13 mm. (3/8 of an inch); 
male, 7-10 mm. (1/4- 3/8 of an inch). 

Eggs, elongate, 33 microns long by 8 microns in 
breadth. Development and hatching are within the 
body of the female (ovoviviparous). The liberated 
embryos measure 600-700 microns in length. 

The life history is not known. 

This species infests the submucosa of the stomach 
of the horse. They are usually in the right sac, and 
their presence may be recognized by oval or rounded 
prominencfes varying in size from that of a hazel nut 
to that of a walnut. The mucous membrane covering the tumors is 
unaltered with the exception of a number of perforations at the summits 
which communicate with the contained cavities. Within these cavities 
are lodged the worms which, on pressure upon the tumor, are extruded 
together with a purulent matter. 

It is probable that the worms reach their submucous lodgment as 
embryos by way of the gastric crypts, the irritation of their presence 




Fig. 127.— Setaria 
labiato-papillosa.male 
at left, female at right. 



246 PARASITES OF THE DOMESTIC ANIMALS 

setting lip proliferative changes with the formation of prominences. 
Outwardly the tumors are limited by the muscular layers of the stom- 
ach, the connective tissue involved being that of the subnuicosa. In 
old tumors the walls become of a dense fibrous character, taking some- 
what the consistency of cartilage. In these no worms may be found, or 
there may be a few of their disintegrated bodies contained in a small 
amount of purulent material. 

Essentially the presence of such parasites can only be revealed post- 
mortem. The tumors are not as a rule numerous, and do not seein to 
cause any serious disturbance. 

The manner of infestation by the worms is not known, nor is it known 
whether they multiply within the tumors. 

3. Habronema microstoma (Spiroptera microstoma). Filariidte 
(p. 244). — This species is larger than the preceding and may also be dis- 
tinguished from it b.y the absence of the constriction behind the cephalic 
extremity. The mouth presents a notch on each side, and there are two 
lateral lips. The tail of the male is rolled spirally, has two lateral wings, 
and a varying number of papilliE. There are two spicules. The vulva 
of the female is situated near the anterior third of the body. 

Length of female. 12-27 mm. (1/2-1 inch); male, 10-20 mm. (3/8-3/4 
of an inch). 

The eggs are elongate and truncated at their extremities. They are 
45—49 microns long by 16 microns wide. Development and hatching 
are within the Ixxly of the female (ovoviviparous). The liberated em- 
bryos measure 90-(t8 mit'rons in length. 

The life history is not known. 

Occurrence. — Post-morten insjjection of the interior of the horse's 
stomach will occasionally reveal the presence of these worms in such 
quantity as to cause an undulating movement of the contents of the 
organ, due to their active motion. While most of the worms are free, 
many may be foun<l with their heads inserted in the gastric cry|its of 
the right sac. More or less inflanunatory disturbance of the mucosa 
may thus be set up, in some ca.ses involving ulceration. 

As in the case of the preceding species, infestation with these worms 
can only be revealed when they are bi-ought to light after the death of 
the host. Where a chronic gasti'ic distiu'bance is suspected to be due 
to pai-asites of the stomach, one or two ounces of oil of turpentine may 
be given in two or three pints of linseed oil. 

FiLARiiD^ OF Sheep and Cattle 

1. Gongylonema scutata (Spiroptera scutata). Fig. 128. Filariidse 
(p. 244). — The body is long and filifonn, white or yellowish white, 
striated transversely, and slightly attenuated toward the extremities. 



FILARIID.« 



247 



The mouth has two lateral and four smaller suljmedian papilla. On 
the anterior 1 to 3 mm. of the body are rounded or oval cuticular tuber- 
cles arranged more or less regularly in rows. The tail of the male is 
rolled up and has two asymmetrical wings and two spicules. The vulva 
of the female is situated in front of the anus. 

Length of female, 8-14 cm. (3 1/8-5 1/2 inches) ; male, 3-5 cm. (1 1/4 
2 inches). 

The eggs are oval. Embryonal development is within the body of 
the female. 

Occurrence. — This is a common species found in a large percentage 



z^'^l 





Fig. 128. — Gong}"lonema scutata: a, anterior portion of body, 
dorsal view;_b, posterior extremity of female; c, posterior e.\- 
tremity of male, ventral view; d, same \'iewed obliquelj' from 
left side, — all enlarged (after Ransom, from Neimiann, Bull. 
No. 127, Bureau An. Ind., IT. S. Dept. Agr.). 



of sheep and cattle slaughtered in the abattoirs of this country and 
Europe. It has also been observed in the horse and in the mouth and 
pharyn.x of pigs. It inhabits the mucosa of the esophagus, usually in the 
thoracic portion where it is lodged just beneath the epithelium. Its body 
runs parallel to the long axis of the organ and is disposed in a spiral man- 
ner, giving somewhat the appearance of the wool-fiber of a merino sheep. 
There is no apparent effect upon the health of animals harboring this 
worm. Its only economic importance seems to be in rendei'ing the 
esophagus undesirable for use in meat food products. 



248 PARASITES OF THE DO]MESTIC ANIMALS 

Experiments b^^ Ransom and Hall have shown that dung beetles and 
croton bugs fed upon the eggs of Gongyloncma scutata become infested 
with an encysted larval stage of the parasite. Evidence is thus furnished 
that the mammalian hosts of the worm become infested as a result of 
swallowing insects beariaig the encysted larvs. 

2. Filaria labiato-papillosa (F. cervina). Filariidse (p. 244). — This 
species resembles Selaria labiato-papillosa of the horse, but differs from 
it in the absence of transverse striations of the integument and in the 
caudal papillce of the female, which form a terminal cluster of small 
blunt points, anterior to which are two thick conical papillae. 

Length of female, 6-12 cm. (2 3/8-4 3/4 inches); male, 4-6 cm. 
(1 1/2-2 3/8 inches). 

Development and hatching is within the body of the female (ovovi- 
viparous). The freed embrj-os are 140-230 microns in length. 

This nematode of the ox and deer is found almost exclusively in the 
peritoneal cavitj'. It does not appear to have any effect upon the health 
of its hosts. A worm occasionally found in the ej'e of the ox is con- 
sidered as belonging with this species. 

FlL.\RIID.E OF THE DoG 

1. Dirofilaria immitis (Filaria immitis). Fig. 129. Filariidse 
(]). 244). — The body is white, long, decidedly thread-like, with ends 
having an obtuse appearance. The mouth is small and surrounded by 
six indistinct ])apilkp. The posterior extremit.y of the male is slender, 
rolled si)irally, and bears two small lateral wings. There are two 
spicules. The posterior extremity 'Of the female is obtuse. 

The female is 25 to 30 cm. m length and about 1 mm. in diameter 
(9 3/4 inches by 1/32 of an inch). The length of the male is 12-18 cm. 
(4 3/4-7 inches). 

The embiyos are developed and hatched in the body of the female 
(ovoviviparous). As they enter the circulation they measure 285- 
295 microns in length and have a diameter of about 5 microns. The 
anterior extremitj^ is obtuse, the posterior extremity attenuated and 
slender. 

Occurrence. — Hematic filariasis of dogs, produced by this species, 
has been most frequently met with in China and Japan, about fifty 
per cent, of all dogs in the latter country, it is estimated, being affected. 
It occurs also in other countries, including North America. 

The usual seat of invasion is the blood-vascular S3'stem, particularly 
the right ventricle of the heart, the puhnonarj' arteries being more 
rarely involved. Not infrequently mature filarise are found in the sub- 
cutaneous connective tissue. In the heart and large arteries the worms 
may be found in a tangled mass containing hundreds so interlaced as to 
make it difficult to extricate single individuals. 



FILARIID^ 



249 



Pathogenesis. — The disturbances caused by the presence of the 
mature filarise are principally mechanical. Depending upon their 
number, they more or less interfere with the circulation, iir some cases 
forming a thrombus which may give rise to emboK in the branches of 
the pulmonary artery. In such cases necrotic 
areas in the lungs with abscess formation may 
result. 

The larvse, probably by their toxic products, 
brmg about ansemia with a leucocytosis which, 
depending upon the number of the parasites 
present, may be more or less pronounced. As 
a result of the invasion of the heart, local mani- 
festations of endocarditis are to be looked foi-. 
The heart's action is variously disturbed, lead- 
ing to dropsical conditions accompanied by 
cough and dyspnoea. Nephritis and convul- 
sions may develop as a later com ph cation. If 
the condition terminates in death, it is usuall\^ 
from paralysis of the heart or a general weakness 
followed by complete paratysis. 

Diagnosis. — The parasites may be present 
without causing observable manifestations, 
while, on the other hand, no line of clinical 
sjanptoms can with certainty be attributed to 
such invasion. A more precise diagnosis can 
usually be made by microscopic examination of 
the blood for demonstration of the presence of 
the larvse. Under low magnification, a drop of 
infected blood placed between a shde and a 
coverslip will reveal fine worm-like larvse in 
snake-hke , movements between the corpuscles. 
It is claimed by most investigators that they 
appear in greatest numbers in the peripheral 
circulation during the night, and, therefore, that blood for such ex- 
amination is best drawn during these hours. 

Infection. — The manner of natural infection with this parasite has 
not yet b^en satisfactorily determined. Manson concluded from his 
investigations that the larvse of Filaria bancrofti (F. sanguinis hominis) — 
a blood parasite of man resembling the species under consideration — ■ 
pass into the digestive tract of a mosquito (Culex) when it sucks the 
blood of an affected person. Later the mosquito, after depositing its eggs 
upon the water, dies, the bod.y disintegrates, and the larval filarise are lib- 
erated, man becoming infected bj' drinking the water thus contaminated. 
It has been held that Dirofilaria immitis has a similar development. 




Fig. 129. — Dirofilaria im- 
mitis ; male at left, female at 
right, — natural size (after 
Railliet). 



250 PARASITES OF THE DOMESTIC ANIMALS 

According to Noe, some of the larvse are taken with the infected blood 
into the bodies of blood-sucking insects. From the intestine they 
migrate to the Malpighian tulles where they undergo a certain degree of 
development. In about twelve days from the time they entered the 
bod}^ of the insect they pass through the walls of the Malpighian tubes 
and enter the mouth parts. If the piercing organ of the insect is broken 
during the act of sucking blood, the animal becomes infected, and the 
larvte are carried with the blood or lymph to the heart where they attain 
sexual maturity. 

(irassi demonstrated by his investigations that nearly all of the larvae 
of the filaria of man die in the intestines of mosquitoes, and that the dog 
filaria cannot live in other parasitic insects harbored by dogs. He con- 
cluded, therefore, that the larvae from affected animals reach the water 
directly. 

The prevalence of the disease in low marshy localities points to the 
transmission of hematic filariasis through contaminated water. The 
larviB from affected animals nmy reach the water with the excrement, the 
urine, or, occasionally, with blood from wounds. In such case infection 
may be direct oi' after the larvie have undergone a further development 
in an intermediate small crustacean, as Cyclops, the parasites gaining 
<'ntrance to the manmiaiian host by way of the alimentary canal and 
from here reaching the blood stream to be carried by the venous blood 
to the light heart. 

Treatment. — Therapeutic measures in this form of filariasis, espe- 
cially where there is pronounced disturbance of nutrition and circula- 
tion, is unsatisfactory. Nutritious food and the avoidance of exertion, 
conjoined with the administration of heart stimulants and prevention, 
so far as possible, of reinfection, may bring results if the parasites are 
not too numerous or the disturbances occasioned by them are not too 
far advanced. 

2. Spiroptera sanguinolenta (Filaria sanguinolenta). Filariidse 
(p. 241). -Tlu' most prominent characteristic of this worm is its blood- 
red color. Tiic tail of the male is obtu.se, spiral, and has two lateral 
wings. There are two spicules. The tail of the female is obtuse and 
slightly cin-ved. The vulva is situated 2 to 3 mm. behind the mouth. 

Length of female, 6-8 cm. (2 3/8-3 1/8 inches); male, 3-5 cm. (1 1/4- 
2 inches). 

The eggs are thick-shelled, elliptical, and about 30 microns long bj' 
12 microns in width. 

Occurrence and Pathogenesis. — This nematode of the dog is usually 
found lodged in tumors of the esophagus and stomach, though it is 
occasionally niet with in large blood vessels, the lungs, and in lymph 
nodes. The tinnors vary in size from that of a hazel nut to that of a 
pigeon's egg, and usuallj' but few are present. They lie beneath the 



FILARIID.E , 251 

mucosa, which is unaltered with the exception of an opening at the 
tumor's summit. Outwardly, they are limited by the muscular coat. 

Upon incision of the hardened tissue of the tumor it is found to contain 
cavities which, on pressure, yield a purulent fluid with which are ex- 
truded the parasites. A varying number of worms may be found coiled 
up in these chambers, generally from two or three up to twenty. 

Symptoms and Course. — The most characteristic symptom of the 
presence of this worm is persistent vomiting. A fatal termination may 
be brought about from inanition resulting from the repeated vomiting, 
or the gastric tumors may rupture upon the peritoneum and cause a 
fatal peritonitis. 

Development. — Railliet has demonstrated that the eggs retain their 
shells in their passage through the intestines of the dog and reach the 
outside with the excrement. Researches of Grassi have shown that the 
embryos then pass into the body of a cockroach, probably by its feeding 
upon the egg-containing excrement of infected dogs. In the body-cavity 
of this insect he fomid large cysts containing larval nematodes agreeing 
in color with this species. The cysts were fed to dogs which, after two 
weeks, showed on necropsy the young parasites already embedded in 
the mucosa of the esophagus. Natural infection of dogs probably 
occurs by their eating the roaches containing these cjj'sts. 

Treatment. — In the absence of precise symptoms indicating the 
presence of these worms, the diagnosis in practically all cases being made 
post-mortem, there is little to be said as to the treatment of the affec- 
tion. Bismuth or small doses of cocaine may be given as palliative 
treatment for the i-elief of the recurrent vomiting. 

FiLAKIID.E OF THE HoG 

1. Arduenna strongylina (Spiroptera strongylina). Filariidse (p. 
244). — The body is subc>'lindrical and often curved ina semicircle. The 
anterior portion is attenuated, the posterior somewhat broader. The 
cuticle is densely striated transversely. The mouth has two lateral 
lips, each with three lobes leading into a small buccal capsule which is 
followed by a cylindrical pharynx marked with cuticular ridges forming a 
series of spirals. The caudal end of the male is curved, has two imequal 
wings, and five pairs of stalked papillae asymmetrically arranged. The 
spicules are long and very unequal. The vulva of the female is slightly- 
anterior to the middle of the body. 

Length of female, 16-22 mm. (5/8-7/8 of an inch); male, 10-1.5 mm. 
(3/8-5/8 of an inch). 

The eggs are oval, 34-39 microns long by 20 microns wide. They 
have thick shells and contain well-developed embryos at the time of 
oviposition. 



252 PARASITES OF THE DOMESTIC ANIMALS 

The species is parasitic in the stomach and small intestine of the hog. 

2. Physocephalus sexalatus (Spiroptera sexalata). FilariidiB (p. 
244). — The body is subcj-lindrical and slightly tapering anteriorly. The 
head is made distinct by a cuticular inflation extending to the posterior 
end of the pharynx. The mouth has two three-lobed lips, each lobe 
having a rounded papilla and leading into a small buccal capsule. The 
cylindrical pharynx has a spiral band which usually breaks up into 
separate rings in the middle of its course and again becomes spiral toward 
the posterior end. The body of the male is nearly uniform in diameter. 
The caudal extremitj' is twisted spirally and has narrow membranous 
wings which are spiimetrical. There are eight pairs of papillae, of which 
four pairs are jireanal and stalked, the postanal papillte small, with 
short stalks, and close to the tail. The spicules are very unequal. The 
body of the female is thickest near the anus, terminatuig abruptly in a 
blunt point furnished with a small conical tip. The vulva is posterior to 
the middle of the bod}-. 

Length of female, 13-19 nun. (1/2-3/4 of an inch). In the region di- 
rectly anterior to the anus the width is 333-450 microns. The male is 
6-9 mm. (3/16-11/32 of an inch) in length. 

The eggs are oval, 34 bj' 15 microns, slightly flattened at the poles, 
and thick-shellod. They contain well-developed embiyos at the time of 
oviposit ion. 

The siK'cies is parasitic in the stomach and small intestine of the hog. 

In neither of these two species is the life history known. The thickness 
of the egg-shell indicates that the embrj-os are not released until this is 
acted upon l).v the gastric juice of the host, and, therefore, that develop- 
ment occurs without an intermediate host. 

In a report upon his investigations of these worms published in 1912, 
Foster, of the Zoological Division of the Bureau of Animal Industry, 
gives the following summary: 

"Two species of roundworms belonging to the family Filariidse, of 
particular interest to helminfhologists and veterinarians on account of 
their wide distrilnition and frequency of occurrence in American swine 
and the possibility that they may cause serious injury to their host, are 
given special consideration in this paper. 

"One of these species, identified as Spiroptera strongylina, has re- 
cently been placed in a new genus, Arduenna, of which it is the type, 
and several errors regarding the anatomy of this parasite have been 
corrected. Another species, Arduenna dentafa, has been found in China 
associated with Arduenna strongylina, and, although not yet reported in 
American swine, is mentioned in this connection, as further investiga- 
tion maj' reveal its presence in this countrj'. 

"Arduenna strongylina is much more common in American swine than 
it is said to be in Eui'opean swine, and has been found abundantly in 



FILARIIDtE 253 

the slaughterhouses of St. Louis, Chicago, South Omaha, and Kansas 
City, and has also been collected at Benning, D. C, and Bethesda, Md. 

"Specimens of hogs' stomachs received from Chicago showed the 
worms deeply fastened in the submucosa or embedded in necrotic tissue 
near which were deep ulcers. The condition suggested infection with 
Bacillus nea-o-phorus, the inoculation with which might easily result from 
the biUTOwing of the worms; however, owing to the sterile condition of 
the specimens received, this could not be satisfactorilj^ demonstrated. 
A similar diseased condition of the stomachs of hogs in Europe is attrib- 
uted by Von Rfi,tz to infection with Arduenna slrongylina. Under the 
circumstances the worm should be regarded with grave suspicion, and 
general prophylactic measures for the prevention of the spread of the 
infection are suggested. 

"Commonlj'' associated with Arduenna strongylina in this countrj^ is 
another worm, identified as Physocephalus sexalatus, first described by 
Molin from specimens from the peccary (Dicotyles labiatus) from Brazil ; 
also found by him associated with Arduenna strongylina from the wild 
boar in Germany. It is also reported by Von Listow (who apparently 
mistook this species for Arduenna strongylina) and Plana, from Europe, 
and by Railliet and Henry from Madagascar and Indo-China, in the 
former case associated with a severe gastritis. Seurat (1912) has re- 
cently reported this species from the ass and dromedary in Algeria, but 
his statements would seem to require confimiation. 

"According to the writers' experience, Physocephalus sexalatus is 
ahnost as widely distributed as Arduenna strongylina, since out of eight 
lots of specimens of the latter species, specimens of Physocephalus sexala- 
tus were found in all but one. In a mixed infection, however, it has 
never been found as abundantly as Arduenna strongylina. This worm 
has apparently the same habit of injuring the mucosa as has Arduenna 
strongylina, as both species were found in the same necrotic tissue in a 
hog's stomach. It must therefore be considered only less dangerous 
because it is less abundant, and should be subject to the same treatment 
suggested for infestation with Arduenna strongylina." 

Control. — As that part of the parasite's life history external to the 
host is not known, no more than general preventive measures can be 
recommended. The author quoted above suggests the following: 

"1. Hogs suffering from loss of appetite or failing to fatten under 
proper food and hygiene should be examined for evidence of infection by 
killing one or two and looking in the stomach for worms; or, where 
practicable, the feces of the entire herd may be examined microscopically. 

"2. Those swine found infested with stomach worms should be 
isolated from noninfected or presumably noninfected swine in clean 
pens, and the dung removed dail>- and mixed with quicklime or dis- 
posed of by carting it to places to which hogs do not have access. 



254 PARASITES OF THE DOMESTIC ANI1VL4LS 

"3. The noniiifected swine shovilcl not be allowed to remain in the 
same pens formerly occupied by the infested animals, but should have 
clean quarters. The old pens should be thoroughly disinfected with lime 
after removing the dung and burning over the ground where feasible." 

Treatment. -Treatment in such infection is. mainly prophylactic. 
A.s a meilicinal remedy, probably benzine is one of the best. It may be 
given in two to four dram doses in milk, administered as recommended in 
the treatment for ascarids. Areca nut, one grain per pound of body- 
weight, may be given in the same manner. 

FiLARiiD^ OF Chickens 

Of the filaria' harbored by poultry, four species may lie mentioned 
here. As to the first three at l(>ast, there is little of record in this country. 

1. Dispharagus spiralis. Filariidse (p. 244). — The body is generally 
rolled spirally. There are three papillis around the mouth. The tail 
of the male is spiral and is provided with wings. There is but one 
spicule. The female is 9 mm. (3/8 of an inch) and the male is 7 nmi. 
(5/16 of an inch) in length. 

This species lives in the wall of the esophagus and intestines of poultiy. 

2. Dispharagus hamulosus. Filariidse (p. 244). — The body has 
eight denticulated longitudinal wings. The female is 16-25 mm. (5/8- 
1 inch) and the male is 14 mm. (9/16 of an inch) in length. 

This worm has been found in Brazil and in Italy. It is parasitic in 
the gizzard of fowls. 

3. Dispharagus nasutus. I-'ilariidie (p. 244). — The body is slightly 
attenuated at its extremities. There are two long terminal papillse 
on each side of the mouth, from which two flexuous wings have their 
beginning. These ])ass to a distance of 0.6 mm., then curve forward. 
The male is filiform, with caudal extremity spiral. There are two 
imefjual spicules. The vulva of the female is in the anterior portion of 
the body. The female is 5-9 mm. (3/16-3/8 of an inch) and the male 
is 5 nun. in length. 

It inhabits the gizzard of fowls. 

4. Tetrameres fissispina iTropisurus fissispinus). Filariidse (p. 244). 
— This species is characterized liy a marked sexual dimorphism. The 
male is white, .slender, 3-6 mm. (1/8-1/4 of an inch) in length, and bears 
U|ion the median and lateral lines spines forming four longitudinal series. 
The body of the female is suliglobular, 2 mm. in length bj^ 1-2 nun. (in 
width; reddish in color; tail short and conical. 

The sjiecies is foimd in the proventriculus of the domestic duck where 
it inhabits subnuicous cysts and may set up a serious inflammation of 
these parts. It is said to be quite common in parts of New York State, 
and it is probalile that it exists in other localities. 



CHAPTER XXI 

NEMATODA. FAMILY V. STRONGYLID.E. SUBFAMILY I. 

METASTRONGYLIN^ 

Worms of the Respiratory Tract 

Nematoda (p. 217). — The most prominent character by which this 
family may be recognized is the caudal bursa of the male which is usually 
well developed. The body is elongate, cylindrical, and in some cases 
filiform. A buccal capsule may be present or absent and may be armed 
with teeth in its interior. The esophagus is more or less enlarged poste- 
riorly. The males have a more or less well-developed caudal bursa, 
usually divided into lateral lobes, each supported by ray-like chitmous 
thickenings. There are two equal or unequal spicules. The vulva of the 
female may be posterior or anterior to the middle of the body, usually 
posterior, in some cases near the anus. 

Parasitism. — While these worms in their adult form mostly infest 
the lumen of the alimentary and respiratory tracts, other organs may be 
primarily or secondarily involved. The subserous larval phase of in- 
testinal invasion by the genus ffisophagostomum and the vascular 
larvae of Strongylus vulgaris may be mentioned in this connection, while 
other organs are not uncommonly invaded by migration. The term 
strongylosis is a general one which has been applied to any helminthiasis 
produced b.y strongyles. It is more precisely used when qualified by 
terms indicating the seat of invasion, as gastric, intestinal, bronchial, 
vascular, or renal strong5dosis. 

Being responsible for some of the most depletive and fatal forms of 
parasitism, the strongyl worms have especially demanded study and 
investigation; this has established important advances in knowledge 
as to their pathogenicity, though much remains to be revealed as to 
their life histories and consequently as to effectual means for their 
control. In general it may he said that low marshy pasturage and wet 
seasons favor infestation with strongyles, which woidd incHcate that the 
ova and embryos of some forms at least are spread by water, and that 
contaminated water and herbage are the vehicles by which the parasites 
reach their hosts. 

As in other parasitic invasions, age and physical conthtion have a 
decided influence in predisposition to strongylosis. Young ruminating 
animals are especially susceptible to the broncho-pulmonary form, 
while in all animals which mav be affected both vouth and senilitv favor 



256 PARASITES OF THE DOMESTIC ANIMALS 

intestinal infestation. Again, the general rule apjilies that resistance is 
alwa.vs reduced in animals in low physical condition, while, essentially, 
crowding and general unsanitary conditions favor the transmission and 
spread of the parasites. 

Of the Strongylidfe three subfamilies may be distinguished, viz: 

Subfamily I. Metastrongylinse. 

Subfamily II. Trichostrong,ylinse. 

Subfamily III. Strongj-linse. 

Subfamily I. Metastrgngylin.e 

Strong\iidse (p. 255). — This subgroup comprises the strongyles 
parasitic in the respiratory system and some in the circulatory system. 
The buccal capsule is al)sent or very slightly developed. The bursa of 
the male is frequently atypical in structure and number of raj'-s. There 
are two equal spicules. The eggs are in varying stages of development 
when deposited. 

The life history is as j'et unknown. It is probable that infection is 
without intermediate host. Romanovitch and Slavine (1914) found 
that eggs of Didyocaulus filaria when placed in water formed embryos. 
Two uioltings followed, the cuticle being retained and encapsulating the 
larvae, and these when fed to sheep produced infection with the adult 
worms. This would indicate direct development and infection hy the 
worms of this group. 

Bronchial and Pulmoxahy Strongylosis of the Sheep and Goat 

Three species of Metastrongylinse invade the respiratory tract of the 
sheep and goat; a fourth, — Metastrongylus apri — described under 
broncho-pneumonia of the hog, is exceptionally found in the sheep. 

1. Dictyocaulus filaria (Strongylus filaria). Fig. 130. Meta- 
strongylina' (p. 25(3). — The body is white, filiform, slightly tapering at 
posterior extremity-. The anterior extremity is obtuse, without wings; 
mouth cii'cular and without papillae. The bursa of the male is notched 
in front ; spicules short, thick, brown in color, and provided with mem- 
branous wings. The caudal extremity of the female is straight and 
conical; vulva somewhat posterior to the middle of the bod.y. 

Length of female, 5-10 cm. (2-4 inches); male, 3-8 cm. "(1 1/8-3 1/8 
inches). 

The eggs are oval, 112-135 microns in length by 52-67 microns in 
breadth. The}^ contain developed embryos which are liberated in the 
bronchi as the eggs are deposited. 

The embryos are 540 microns long by 20 microns in diameter, tapering 
to a blunt point behind. 



METASTRONGYLIN^ 



357 



The worm is parasitic in the respiratory organs of the sheep, goat, 
camel, and deer. 

2. Synthetocaulus rufescens (Strongylus rufescens). Fig. 131. 
Metastrongyhnae (p. 256). — The body is thin and hair-hke, brownish 
red in color. The mouth has three papilliform lips. The bursa of the 
male is notched in front and has two small lateral indentations. The 
spicules are striped transversety and rounded at their ends. The poste- 
rior extremity of the female terminates in a blunt point; vulva mime- 
diately in front of the anus at the base of a small pre-anal elevation. 



B 






Fig. 131.— 
Sj'nthetocau- 
lus rufescens; 
male at right, 
female at left, 
— natural size. 



Fig. 130. — Dictyocaulus filaria: a, female; b, male, 
natural size; e, anterior extremitj'; d, eggs, — enlarged. 

Length of female, 25-35 mm. (5/8-1 3/8 inches) ; male, 18-28 mm. 
(3/4-1 1/2 inches). 

The eggs are oval, 75-120 microns in length by 45-82 microns in 
breadth. Segmentation has advanced at the time the.y are deposited, 
after which the embryos develop rapidly and are liberated in the pul- 
monary alveoli. From the alveoli they pass to the bronchi and trachea 
from whence they are expelled to the outside where they have a strong 
vitality and are capable of resisting desiccation for a long tune. 

As found in the trachea and larger bronclii, the embryos measure 
300-400 microns in length by 16-18 microns in Ijreadth. 

The worm is parasitic in the resphatory organs of the sheep, goat, and 
rabbit. 



258 PARASITES OF THE DOMESTIC ANIMALS 

3. Synthetocaulus capillaris (Strongylus capillaris). Metastrongy- 
linae (p. 256). — This worm like the prececUng is thin and brownish in 
color. The mouth has six papilla and the caudal extremity is pointed. 
The caudal extremity of the male is curled spirally; bursa small and sup- 
ported ]jy seven ribs; spicules dentate. The vulva of the female is just 
in front of the anus. 

Length of female, 20-22 mm. (7/8 of an inch); male, 14 mm. (9/16 of 
an inch). 

The eggs are brownish in color. The embryos develop after the eggs 
are dejiosited and arc liberated in the pulmonary alveoli and bronchi. 
After depositing the eggs the adult worms invade the lung tissue where 
they die and become encapsulated. 

The worm is parasitic in the respiratory organs of the sheep and goat. 

Bronchial and pulmonary strongylosis of sheep and goats is due to 
the i)resence of these worms together with their eggs and larva; in the 
air ]xissages and alveoli. The affection is usually a broncho-pneumonia, 
though the symptoms presented will be somewhat subordinate to the 
infecting species. If the infection is with Didijocaulus filaria, or this 
dominates a pulmonary species coexisting in the same animal, the 
bronchial symptoms will be the more prominent. On the other hand, 
in an abundant infestation with Synthetocaulus rufescens the pulmonary 
s>in])t()ms are likely to predominate. 

Symptoms. — Bronchial strongylosis of sheep and goats is usually 
due to the presence of adults of the species Dictyocaidus filaria in the 
larger air passages, and in most all cases the pulmonary form is asso- 
ciated with it. In general, the sjinptoms are those of a bronchial 
catarrh. There is a short dry cough which at fii'st is at long intervals. 
Later this is more frequent and may become paroxysmal and accom- 
panied by distressing attacks of dyspncea. The bronchial secretion 
expelled through the mouth and nostrils is frequenth^ lumpy and usually, 
though not always, contains the worms with their eggs and embryos, 
the latter found by examination of the material with the microscope. 
At first the liveliness and appetite of the annual are retained and there 
is no api)r('ciable loss of flesh. If the number of the parasites remains 
.small there will contimie to be little or no manifestation of their presence. 
Relative to the degree of infestation, the .synnptoms may pass through 
the gradations above given to extreme difficulty in respiration, emacia- 
tion, pallor, and edema of the larj-nx, muzzle, and eyelids, the brisket 
and other dejDendent parts of the body in some cases also becoming 
edematous. Finally, in extreme weakness, the animal is unable to get 
upon its feet and, in a condition of complete prostration, succumbs. 

Syinptoms occasioned by the presence of strongj'les in the pulmonary 
air spaces and alveoli are in themselves less prominent than those of 
verminous bronchitis. Attentive percussion over the thorax maj' reveal 



METASTRONGYLIN^ 259 

dullness in circumscribed areas, but as a rule it shows nothing abnormal. 
Usually sjariptoms are only observed upon the appearance of cachexia 
and weakness following the development of purulent areas in the lung 
tissue, this finally bringing about the death of the animal. 

Course and Prognosis. — The duration of broncho-pulmonary stron- 
gylosis varies according to the number of parasites present and the 
toleration of the affected animal. In the majority of unfavorable cases 
the disease will run a course of two, three, or four months. In the very 
young this period may be much shortened, the animal succumbing in a 
few days from the first observation of symptoms. Strong adult animals, 
on the other hand, are likely, unless there is reinfection, to gradually 
recover during a course of six to eight months. In anj^ case where the 
symptoms are well marked a fatal termination is to be looked for. 

For Post-mortem Appearance, Development and Etiology, Control, 
and Treatment, refer to pp. 262-265. 

Bronchial and Pulmonary Strongylosis of Cattle 

Dictyocaulus viviparous (Strongylus micrurus). Fig. 132. Meta- 
strong}dina3 (p. 256). — The body is long, slender, and attenuated at both 
extremities. The liead is rounded and without wings; 
mouth circular and nude. The bursa of the male is 
small, without lobes, and is supported by five ribs. 
There are two short and strong spicules. The tail of 
the female terminates in a sharp point; vulva near the 
posterior sixth of the body. 

Length of female, 6-8 cm. (2 3/8-3 1/8 inches); 
male, 3.5^ cm. (1 3/8-1 5/8 inches). 

The eggs are oval, 85 microns in length by 35 mi- 
crons in breadth. Embryos are developed within the 
bodj^ of the. female and are liberated at the time the 
eggs are deposited. 

The liberated embryos are 256 microns long by 25 
microns in thickness. They pass from the bronchi 
to the trachea from which they are expelled to the 
exterior. 

Symptoms. — In light infestations no symptoms 
maj' be observed save an occasional cough. When 
the parasites are more numerous the cough becomes t3-ocauius "^dvipar- 
more frequent and sonorous, and, in the further course, ous; male at right, 
paroxA^smal, the animal extending the head, protruding f*^™"'? ^t l^'ft- ^it- 

, ' 1.1 1. • , • , 1 ural size. 

file tongue, and treelj^ salivating during the attacks. 

The paroxysms are accompanied by dyspncea and suffocation, with 

beating flanks, quickened pulse, and injected conjinictiva. In severe 



260 PARASITES OF THE DOMESTIC ANi:\L\LS 

cases with violent attacks occurring several times a day, the gasping 
aninial may fall prostrated and die from asphj-xiation. 

The mucus expelled by the coughing is frequently streaked with 
blood and contains the worms which are often collected in masses. It 
is to these masses obstructing the large bronchi that the suffocation is 
due. 

Course and Prognosis. — What has been said as to influences gov- 
erning the duration and intensitj' of the malady in sheep will, in general, 
appl\' to cattle also. The prognosis, especially in calves, is usually 
unfavorable. Death is generallj- brought about in three to six months 
b}^ asphj-xia or extreme cachexia and exhaustion. 

For Post-mortem Appearance, Development and Etiology, Control, 
and Treatment, refer to pp. 262-265. 

Bronchial and Pulmonary Strongylosis of the Pig 

Two strong\-les aie met with in the res])iratory tract of the hog. 

1. Metastrongylus apri (Strongylusapri; St. paradoxus). Fig. 133. 
Metastrongjdinse (p. 256). — The body is white or brown. The mouth 

has six lips. The bursa of the male is bilobate, each lobe 
sustained by five ribs. The spicules are slender and veiy 
long, measuring about 4 mm. (3/16 of an inch) and each 
terminated in a barb. The tail of the female terminates 
b}' a short hook-like process. The \ailva is on a slight 
emmence immediately in froi4 of the anus. 

Length of female, 2-5 cm. (3/4-2 inches); male, 1.2-2 
cm. (1/2-3/4 of an inch). 

The eggs are oval, 57-100 microns in length bj' 39-72 
microns in breadth. They contain developed embr.yos at 
the time they are deposited and these are liberated in 

Mrtastrotf Tus *^^ bronchi. 

apri;'' ma°e at The embryos at the time of their liberation measure 
right, female at 220-250 microns ill length and 10-12 microns in thickness. 
I e f t ,— natural rpj^g worm is parasitic in the respiratory tract of do- 
mestic and wild hogs, occasionallj' of sheep. 

2. Metastrongylus brevivaginatus. ^Metastrongylina? (p. 256). — 
This species has for a long time been confounded with the preceding 
under the name of Slrongijlus paradoxus. It differs from it in the shape 
of the bursa and in the spicules which are short, each terminating in 
two barbs. 

The worm is parasitic in the respiratory tract of domestic hogs. 

Occurrence and Symptoms. — While the presence of strongyles in 
the bronchi of pigs has Ijeen known for a long time, it is not as frequently 
observed in these animals as in sheep and calves. Heavy infestations 



METASTRONGYLINiE 261 

with Metastrongylus apri sometimes occur with high mortality among 
pigs. Such cases take a course similar to that in sheep and calves. In 
the milder cases there may be disturbances of nutrition and occasional 
cough, though usually in light invasions nothing is observed to cause 
suspicion of the presence of the worms which are only revealed on 
examination of the respiratorj'' passages after slaughtering. 

For Post-mortem Appearance, Development and Etiology, Control, 
and Treatment, refer to pp. 262-265. 

Bronchial and Pulmonary Strongylosis of the Horse 

Dictyocaulus arnfieldi (Strongylus ariifieldi).^Metastrongylinse 

(p. 256). — The body is white and filiform and the mouth is nude. The 
bursa of the male is short, with faint lobulation. The spicules are 
slightly arched, 200-240 microns in length, and have a net-like marking. 
The tail of the female is short, slightly curved, and termmates in a 
blunt point. The vulva is situated somewhat posterior to the middle 
of the bodj' and is not prominent. 

Length of female, 4.3-5.51 cm. (1 11/16-2 3/16 inches); male, 2.8- 
3.6 cm. (1 1/8-1 7/16 inches). 

The eggs are oval and measure 80-100 microns m length bj' 50-60 
microns in breadth. They contain developed embryos at the time they 
are deposited, and these are hberated in the resi^iratory passages of the 
host. 

The liberated embiyos measure 400-490 microns in length and have 
a thickness of 14-18 microns. 

The worm is parasitic in the bronchi of the horse and ass. 

Bronchial strongylosis of equmes seldom occurs. CHnically it is 
manifested by sjanptoms suuilar to those of verminous bronchitis in 
other animals. 

For Post-mortem Appearance, Development and Etiologj-, Control, 
and Treatment, refer to pp. 262-265. 

Cardio-Pulmonary Strongylosis of the Dog 

Haemostrongylus vasorum (Strongylus vasorum). Metastron- 
gylinse (p. 256). — ^The body is filiform, wliitish or reddish m color, and 
has longitudinal striations. The mouth is nude. The bursa of the male 
has two lobes, each sustained by four ribs. The \aih'a of the female 
is situated in front of the anus. 

Length of female, 18-21 mm. (3/4-13/16 of an inch); male, 14-18 mm. 
(9/16-3/4 of an inch). 

The eggs are oval and measure 70-80 microns in length by 40-50 
microns in breadth. Segmentation occurs after they are deposited. 



262 PARASITES OF THE DOMESTIC ANIMALS 

When freed fioin the eggs the embryos measure 300-360 microns in 
length by 13 microns in thickness. 

The worm Uves in the right heart and ramifications of the jjuhnonary 
artery of the dog. 

Cardio-puhnonary strongylosis of the dog is due to the presence of 
these parasites, together with their eggs and enibrj'os, in the right 
ventricle of the heart and small ramifications of the pulmonary" 
artery. 

Symptoms. — Symptoms in this form of strongylosis of the dog are 
obscure, and generally the disease is not recognized until post-mortem 
examination of the animal. Resjiiratory disturbances occur in some 
cases, and there may be the development of ascites. The attacks of 
respii'atory difficulty may disappear after a few days, or they may lead 
to asphyxia and the death of the animal. 

For Post-mortem appearance, refer to page 263. 

PcLMOXARY Strongylosis of the Cat 

Synthetocaulus abstrusus (Strongylus pusillus). Metastrongylinae 
{p. 2o()). — TIic body is filiform and the mouth is without papillae. The 
bursa of tlie male is short and slightly festooned. The spicules are slen- 
der, long and lecurved. Tlie caudal extremity of the female terminates 
in a blunt point; vulva immediately in front of the anus. 

I>engtli of female, about 10 mm. (3/8 of an inch); male about 5 mm. 
(3/lGof an inch). 

The eggs are oval or sul)glol)ular, (JO-85 microns in length by 35-80 
microns in breadth. Segmentation occurs after they are deposited. 

The liberated (>mbryos are 370-450 microns in length by 16-18 
microns in diameter. 

Tlie worm is parasitic in the lungs of the cat. 

Symptoms. — \'crniinous pneumonia of cats produced by the ova and 
embryos of tiiis worm not infequently occurs without symptoms by 
which it maj' be recognized. On the other hand, the animals may have 
a frequent cough accompanied by vomiting. Where emaciation and 
diarrhea follow ujion such symptoms, death will usually result after a 
course of two to three months. 

PosT-MoRTEM Appearance in Bronchial and Pulmonary 
Strongylosis 

Animals which have died as a result of strongyles in the respiratory 
passages will, upon necrops.y, show an abundant collection of mucoid 
and nuicopurident material in the bronchial tubes which is frequently 
streaked with blood and contains the adult worms, ova, and embrj'os. 



METASTRONGYLIN^ 263 

The worms may be in masses sufficient to obstruct the medium-sized 
or larger bronchi which in places may present sac-like dilations con- 
taining bundles of worms together with more or less purulent mucus. 
The mucosa of the heavily infested bronchi is edematous and may show 
hemorrhagic streaks. In the vicinity of bronchial dilations especiallj' 
there is prohferation of connective tissue, the air-containing tissue 
being compressed and obliterated and at the periphery sometimes 
showing localized pleuritic adhesions. 

In pneumonia due to the presence of strongyles three forms have 
been distinguished, viz: 1. A lobar pneumonia due to the presence of 
the adult worms in the ramifications of the bronchi. 2. A diffuse pneu- 
monia due to ova and embryos which invade the pulmonarj' tissue in 
large numbers. 3. A nodular or pseudo-tuberculous pneumonia due 
to the accumulation of eggs and embryos in circumscribed parts of the 
lungs. The last is the most common form and is characterized by the 
presence of small, hard, grayish yellow centers from the size of a millet 
seed to that of a pea which may be more or less confluent. Most of 
these nodules are found toward the periphery of the lungs, particularh' 
at the margins and just beneath the pleura. Generally they adhere 
closely to the sun-ounding tissue, varying in color from yeUow, grayish 
yellow, reddish brown, violet, or black according to their age and the 
character of the inflammatory process. All of the centers become caseous 
and finally undergo calcareous infiltration. 

In addition to the bronchial and pulmonar.y lesions there are presented 
in severe cases the evidences characteristic of anaemia and cachexia, 
involving subcutaneous edema and serous exudate in the ca\dties of the 
body. 

Dogs which have suffered from cardio-puhnonary strongylosis will, 
on necropsy, reveal adult worms {Hcemostrongylus vasorum) in tire right 
heart and branches of the puhnonary artery. The lungs at the bases of 
their lobes' show circumscribed granular areas in which the tissue is 
graj^, compact, and heavier than water. The granules are hardly the 
size of a pin's head, semi-transparent, and give a roughened aspect to 
the surface. About the eggs and embryos lodged in the small arterioles 
there are found small pseudo-follicles which, on histological examina- 
tion, will exhibit three zones, — (1) a central consisting of a giant cell 
containing 'a segmented egg or embryo; (2) a middle of epithelial cells; 
and (3) a peripheral consisting of embryonal tissue elements disposed 
circularly. Larger nodules may be found, usually in close relationship 
to a clot in a branch of the puhnonary artery in the vicinit\' of which 
there is an accumulation of adult strongyles. 

Development and Etiology. — The lungworms deposit their eggs in 
the respiratory passages of their host and the freed embryos are either 
expelled directly with the bronchial secretion or, passing to the pharynx. 



264 PARASITES OF THE DOMESTIC ANIMALS 

are swallowed and reach the outside with the feces. Further than this 
little is known as to their Ufe liistor.y. The larvae do not appear to pass 
through any stages of development in the bronchi of their host, the first 
phases of their existence probably requiring that they be expelled from 
the animal. 

Having reached the outside, if the larvse encounter sufficient warmth 
and moisture, they molt and this is later followed by a second molting 
after which they retain their coverings and in this condition may resist 
desiccation for a long time. It is probable that the larvae find their 
way to a host with the wet grass and, especially in the case of sheep, 
with collections of water upon the pastures which the animals drink. 
The view as to direct development and infection is supported by the 
investigations of Romanovitch and Slavine (p. 256), and it seems 
proljable that in all cases of bronchial and pulmonary strongylosis the 
infection is direct. Some authors, however (Cobbold, Leuckart), be- 
lieve that a portion of the larval stage is lived in an invertebrate host, as 
an earthworm, larval insect, or mollusc. 

The larvae are usually taken up by the host animals in the spring, 
though it is probable that infection may occur at any time during the 
pasture season. That infection cannot occur directly from animal to 
annual has been demonstrated by Leuckart, Herms and Freeborn and 
others who were not successful in bringing it about by the introduction 
into the respirator}' passages and stomach of bronchial mucus containing 
numerous embryos. 

The com-se of the larval worms in reaching the bronchi after natural 
infection by way of the digestive organs has not been demonstrated. 
Based upon the function of rumination and the peculiar susceptibility 
of ruminating animals, the invasion of the air passages has been attrib- 
uted to the i-egurgitation of contaminated food, the worms passing 
from the phar\'nx to the larynx and trachea. But this hj'pothesis seems 
to have no more than J^lausibilit^- in its support, and certainly cannot 
well ajijily to the case of the non-ruminating hog. 

Control. — In districts where bronchial and pulmonary strongylosis 
prevails, low, marshy and wet pastures or parts of pastures should not 
be accessible to susceptible animals. Drainage and a liberal covering 
of the groimd with lime phosphates will do much to destroy the larvae. 
Bearing in mind that .young animals are more susceptible to attack than 
older ones, it is advisable where the disease prevails to give them feed 
and water each day before they are turned upon pasture. This will in a 
measure prevent them from going to pools and marshy places for water 
where they are likely to linger and graze vmless their night's fast has 
been previously somewhat broken. Where hogs and cattle are con- 
cerned the pens, stables and drinking places should be repeatedly cleaned 
and disinfected. Sputum, feces and bedding are not to be placed 



METASTRONGYLINiE 265 

with manure to be spi-ead upon the fields, but should be collected and 
burned as should also the infected respiratoiy organs of slaughtered 
animals. 

Treatment. — Treatment with a view to attacking the worms by way 
of the digestive tract with remedies supposed to act by their excretion 
through the lungs can at most be but mildly successful. Administered 
in this waj'', a sufficient quantit}' of the anthehnintic to be effectual would 
probably mclude the host in its destructive effect. 

Fumigation with various substances has been recommended and 
widely practiced. This procedure has more to recommend it than the 
first mentioned in that the remedy reaches the worms directly, having 
such a deleterious action upon them that thej' are more readily expelled 
in the coughing induced bj^ the irritant smoke and vapors. Again an 
objection to the method is the intensity of apphcation required for its 
success, this demanding that the anunals be subjected to the fumes until 
they are dangerously close to asph3^ation. 

Where the fumigation treatment is resorted to it should be carried 
out in a tightly closed building to accommodate not more than fifty 
lambs at a time. Among the various substances which have been used 
to generate the fumes are tar, creolin, asafetida, horns, hoofparings, hair 
and the vapor of heated oil of turpentine. The intensity and duration 
of the treatment should be governed by the size and vigor of the anunals 
and according as they become accustomed to it. At first it should not 
be applied for more than a few minutes each daj^; later two or three 
treatments of ten or more minutes duration each may be given daily. 
During the fumigation the anunals should be closely watched for evi- 
dences of asphyxiation. 

Of agents for creating the fumes, tar, sulphur and turpcntme may be 
mentioned as probably among the best. These maj' be placed upon 
hot coals contained in a pot suspended by a cham from the ceiling m 
such manner that it will be just bej'ond the reach of the annuals' heads. 
The fumes should fill the entire enclosure and can be maintained by 
adding more of the ingredients as required. 

A more successful method of treatment is by tracheal injections of 
liquids which will kill the worms or reduce their ^-itality to a sufficient 
degree that they may be easily expelled. This procedure is espe- 
cially to be recommended for calves and is equally effectual for lambs, 
though where flocks of considerable size are involved, it is not so 
practicable. 

The measure of success attained bj' such treatment will depend largely 
ui:)on the degree to which the worms and their larvce have penetrated to 
the deeper parts of the respiratory organs. The solutions used nuist 
reach their destination by gi-avity, aided somewhat by the currents of 
ins]-)ircd air, so that ultimately' they will probably pass no further than 



26G PARASITES OF THE DOMESTIC ANIMALS 

to the anterior portions of the lungs, the more deeply loilged parasites 
remaining unaffected. Furthermore, where an air passage is occluded 
by a nmcus plug and mass of worms, the remedy will not pass bej'ond 
the obstruction and, therefore, cannot reach the further ramifications of 
the passage. 

Probably acjueous solutions for intratracheal injection have an ad- 
vantage in more readily becoming diffused. Oily preparations do not 
penetrate so deeply nor do they mix with the mucus. On the other hand, 
it is to be said in their favor that they arc not so readily absorbed as 
aqueous solutions and remain in the air passages longer. The use of 
both aqueous and oil.y mixtures conjointly might well be recommended. 

Among the numerous formulae for intratracheal injection the following 
may be mentioned; (1) Iodine two parts, iodide of potassium ten parts, 
distilled water one hundred parts. MLx and make into an emulsion with 
equal imrts of oil of turpentine and olive oil. Give one to two drams to 
each sheep; calves three to four drams. Two injections with an interval 
of two days may be sufficient. (2) One per cent, aqueous solution of 
carbolic acid. Sheep one to one and a half drams, calves three to five 
drams. Inject once daily for several successive days. (3) Creolin five 
parts, oil of tujientine and olive oil of each fifty parts. Sheep one to 
one and a half drams, calves three and a half to five drams. Inject once 
clail\- for three successive days. (4) Creosote twenty parts, oil of amyg- 
dala one hundred parts. Calves one to one and a half drams. Inject 
once daily for fom- days. 

The intratracheal injections should be made slowl>' with a curved 
needle of large caliber or with a curved trochar. Previous to the opera- 
tion the wool should be shaved or closely clipped from the region. The 
needle shovild enter between the tracheal rings, preferably after a .small 
incision has been made in the skin. 

Based on experiments which they carried on for over one year (1914), 
involving about two hundred and fifty animals, Herms and Freeborn 
conclutled that chloroform administered nasally is, under proper condi- 
tions, a valuable method of treatment. The chloroform is introduced 
first into one nostril, then into the other, with an all glass syringe or 
medicine dropper in doses sufficient to nearly ana'sthetize the animal, or, 
in other words, until it becomes "groggy." The dosage required for 
this will depend upon the animal's susceptibility, and therefore cannot 
be exactly given. It is stated as varying from twent.y-three to forty-six 
drops for angora goats, and from sixty to one hundred and sixty-five 
drops for calves, one-half the quantity in each nostril. The treatment is 
to lie repeated at five or six day intervals until recovery, which, \mder 
good conditions of food and shelter, should not require more than three 
injections. Experiments by the investigators mentioned have shown 
that, while the worms were not killed immediately, death and disin- 



METASTRONGYLINiE 267 

tegration of most of them occurs a few hours after the administration of 
the chloroform when large numbers are expelled in coughing. 

Whatever procedure may be adopted in the treatment of broncliial 
and pulmonary strongylosis, or if treatment is not attempted, it is liighly 
important that the animals receive plenty of nourishing food and that 
they be well sheltered against cold and wet weather. 



CHAPTER XXII 
NEMATODA. SUBFAISIILY II. TRICHOSTRONGYLINtE 

Worms of the Stomach and Intestine 

Strongj-lidce (p. 255). — These strongj^les are parasitic only in the 
aliincntarj- canal. The mouth is simple and without a buccal capsule 
(Fig. 135). The body is generally straight or it may be somewhat 
curved. The eggs are generally segmented at the time they are de- 
posited. Development is direct, and infection, so far as known, is only 
by ingestion. 

Gastro-Intestinal Strongylosis of the Sheep and Goat 

1. Haemonchus contortus (Strongylus contortus). Fig. 134. 
Trichostrongyliiuc (]). 268). — The body is filiform, attenuated at the 
extremities, and red or white in color. The integument is striated 
transversel}-. Near the anterior extremity there are two lateral tooth- 
like papilla directed backward. The bursa of the male has two long 
lobes and a small lobe accessory to the i-ight (Fig. 136): there are two 
spicules. The tail of the female is acutely pointed; anterior extremity 
more gradually attenuated; vuh'a toward posterior fifth of the body. 

Length of female, 18-30 mm. f 11/16-1 3/16 inches); male, 10-20 mm. 
(3/8-3/4 of an inch). 

The eggs are elongated oval and measure 70-95 microns long by 
43-54 microns wide. According to Railliet they contain developed 
embryos at the time of deposition. Hatching jirobably takes place in 
water, the embryo at the time of its release measuring 300-400 microns 
in length by 17-21 microns in breadth. Infection is probably by drinking 
water and contaminated pasturage bearing the larva?. 

The worm is parasitic in the aljomasum and duodenum of sheep, 
goats, and cattle. 

2. Cooperia curticei (Strongylus ventricosus; St. curticei). Fig. 
137. Trichostrongylinie (p. 268). — The anterior end of the body is 
usually coiled spirall.v. The cuticle at the region of the head is striated 
transversely; cuticle of remainder of the body exhibits fourteen to six- 
teen longitudinal lines. The mouth is small and not well defined. The 
bursa of the male has two lateral lobes and a small median lobe. The 
spicules are short. The vulva of the female is close to the posterior end 
of the body. Tail slender and acutely pointed. 



TRICHOSTRONGYLIN.E 



269 




: \—-C.p. 




-A—i/it. 



Fig. 134.— 
Haemonchus con- 
tortus, female. 
♦Vulva, xo. (Af- 
ter Ransom, Bull. 
No. 127, Bu. 
An. Ind., 'U. S. 
Dept. Agr.). 



nv.l. 



Fig. 136. — HEemonchus contortus, — enlarged, 
Posterior extremity of male, dorsal view; d. 
dorsal ray supporting the asymmetrically 
situated dorsal lobe of bursa; e. d., externo- 
dorsal ray; e. 1., externo-lateral ray; gub., 
gubernaculum ; 1. v., latero-ventral ray; m. 1., 
medio-lateral ray; p. I., posterolateral raj^; 
sp., spicule; v. v., ventro-ventral ray (after 
Ransom, Bull. No. 127, BureauAn. Ind., U. S. 
Dept. Agr.). 



Fig. 135.— HEemon- Length of female, about 6 mm. (1/4 



chus contortus, an- of an inch) : male about 5 mm. (3/16 

terior portion of „f „ „ ;„„u\ 

body, -enlarged: c. of an llich). 

p., cervical papilla; 

es., esophagus; int., 

intestine; n. r., nerve 

ring (after ■ Ransom, 

Bull. No. 127, Bu. 



The eggs are oval, 63-70 microns in 
length by 30-32 microns in width, seg- 
mented at time of deposition. 

The worm is parasitic in the small 
An. Ind., u. S. Dept. intestine, more rarelv the abomasum, 

Agr.). " 

of the sheep and goat. 
3. Ostertagia marshalli. Fig. 139. Trichostrongjdinffi (p. 268). — 
The mouth is small and surrounded by sLx indistinct papillse. The 
cuticle has twentj^-five to thirty-five longitudmal ridges appearing as 
lines. Cervical papillae 340^15 microns from anterior end of the body. 
The bursa of the male is bilobate; spicules short and similar, yellowish 
brown in color. The tail of the female is slender, gradual!}' tapering, 
and rounded at the tip. The vulva is a transverse slit located near the 
tail extremity. 



270 



PARASITES OF THE DOMESTIC ANIMALS 





Fig. 137. — Cooperia curticei; male at 
right, female at left. *Vulva. xl5. 
(After Ransom, Bull. No. 127, Bureau' 
An. Ind., U. S. Dept. Agr.). 




Fig. 138.— Co- 
operia curticei, 
aaterior portion 
of body, lateral 
view. xSOO. (Af- 
ter Ransom, Bull. 
No. 127, Bureau 
An. Ind., U. S. 
Dept. Agr.). 



Fig. 139. — Ostcrtagia marshalli; male at right, female at 
left, enlarged (after Ransom, Bull. No. 127, Bureau An. Ind., 
V. S. Dept. Agr.). 



TRICHOSTRONGYLINiE 



271 



Length of female, 12-20 nun. (1/2-3/4 of an inch); male, 10-13 mm. 
(3/8-1/2 an inch). 

The eggs are oval, 160-200 microns in length by 75-100 microns in 
breadth. 

The worm is parasitic in the abomasum, rarely the small intestine, 
of the sheep. It was first collected by Dr. H. T. IMarshall and Prof. 
V. K. Chestnut in Montana. 

4. Trichostrongylus instabilis (Strongylus colubrif ormis ; St. in- 
stabilis). Fig. 140. Trichostrongyhna? (p. 208).— The body is small, 
slender, gradually attenuated forward from 
posterior fifth; color reddish. Cuticle trans- 
versely striated; longitudmal lines and cer- 
vical papillaj absent. The bursa of the 
male is large and laterally lobed; spicules 
short, spatulate, and appearing as though 
twisted. The body of the female is but 
slightty thinner toward the anus; behind 
the anus it suddenly narrows to fonn a 
sharp tail; vulva near middle of posterior 
half of the body. 

Length of female, 5-6 mm. (1/4 of an 
inch) ; male, 4-5 mm. (3/16 of an inch). 

The eggs are oval, 73-76 microns in 
length by 40-43 microns in breadth. 

The worm is parasitic in the duodenum 
of sheep and goats of North Africa, Europe, 
Japan, and LTnited States. In Egjq^t it 
has been observed in man. 

Other species which may be found in 
sheep and goats are Nematodirus filicollis ^i«- 140.— Trichostrongylus in- 

, „ . , , . , . , stabiUs; male at right, female at 

and Loopena oncophora which are referred igft *vulva. xi5. (After Ran- 

tO under gastro-intestinal Strongjdosis of som. Bull. No. 127, Bureau An. 
cattle. Ind.,U.S. Dept.Agr.). 

Occurrence. — Gastro-intestinal strongylosis of sheep and goats is 
generally caused by the presence of Hcemonchus contortus which may 
be in association with one or more other species. This stomach worm 
is recognized as one of the most serious of the numerous pests with 
which the sheep raiser has to contend. Animals of all ages become 
infected, but the most serious effects are observed in lambs and kids. 
Occurring mostly in wet marshy districts and in seasons of frequent rain 
— conditions favorable to the propagation of the lung as well as the 
gastric worms — the affection is frequentlj' associated with the respiratoiy 
form of strongylosis. 

In the United States the stomach worm of sheep, goats, and cattle 




272 PARASITES OF THE DOMESTIC ANIMALS 

is especially prevalent in the Mississippi \'alley, in the region of rivers 
tributaiy to the Mississippi, and in the Gulf States. In parts of the 
Middle West and South the parasite has been such a source of discour- 
agement as to cause the sheep industry to be almost completely aban- 
doned. 

Pathogenesis. — Taken up as larvse with ingested plants or drinking 
water, the worms attack the mucosa of the fourth stomach and feed 
upon the blood of their host. The degree of disturbance which they 
cause will be proportionate to their number. Heavy infestations are 
accompanied by disorders of digestion and lead through loss of blood 
to anemia, dropsy, and emaciation, the general morbid effect being 
contriljuted to Ijy the toxins elal)orated by the parasites. 

Symptoms. — The symptoms are those of a pernicious anaemia. The 
infected animal becomes dull and spiritless and there is arrested develop- 
ment. The apjjetite is diminished and depraved, and the animal fre- 
quently seeks water to quench an intense thirst. The anaemia is revealed 
in tiie paleness of the skin and visible mucous membranes and in the 
edematous swellings in dependent parts of the body, often under the 
lower jaw. Later in the course of the disease a diarrhea appears with 
watery dark discharge of putrid odor. In some cases the toxic disturb- 
ances niay be manifested by convulsions or paralysis. Finally, after a 
course of several months, the animal dies in a state of extreme emacia- 
tion and weakness. 

The cause of these sjniiptoms of a progressive anaemia can often be 
no more than suspected, and, where the condition prevails in flocks, a 
more certain diagnosis may l)e made by killing an affected animal and 
examining the fourth stomach. 

For Post-mortem Appearance, Development, Control, and Treat- 
ment, refer to pp. 275-279. 

Gastro-Intestinal Strongylosis of Cattle 

Several species of strongyles ma.y occur in the abomasum of cattle- 
Of these the most important are Hcemonchus coniortus, described under 
gastro-intestinal strongylosis of sheep, and the encysted stomach worm, 
OslerlcKjia nstertaqi. 

1. Ostertagia ostertagi (Strongylus ostertagi). Fig. 14L Tricho- 
strongylinte (]). 2GSi. — The body is filiform with attenuated extremities. 
The mouth is small and surrounded by six indistinct papillae; cervical 
papillae present. The cuticle has 25 to 35 longitudinal lines or ridges. 
The bursa of the male is comparatively small and has two lateral lobes 
vmited bj' a small median lobe (Fig. 142). The spicules are short, each 
having two slender barbed processes coming off from the inner side in 
the posterior half. The ^iilva of the female is a transverse slit covered 



TRICHOSTRONGYLIN.E 



273 




m.1. 



Fig. 142. — Ostertagia ostertagi. 
Posterior extremity of male with 
bursa spread out: d, dorsal ray; e. d., 
externo-dorsal ray; p. 1., postero- 
lateral ray; m. 1., medio-lateral ray; 
e. I., externo-lateral ray; 1. v., latero- 
ventral ray; v. v., ventro-ventral ray; 
p. b. p., pre-bursal papilla; sp., spi- 
cules. xlSO. (After Ransom, from 
Railliet, Bull. No. 127, Bureau An. 
Ind., U. S. Dept. Agr.). 




Fig. 141. — Ostertagia oster- 
tagi; male at right, female at 
left. * Vulva. xl5. (After Ran- 
som, Bull. No. 127, Bureau An. 
Ind. U. S. Dept. Agr.). 



by a prominent cuticular flap; it is located 
close to the caudal extremity of the body. 
The tail tapers gradually and ends in a slen- 
der tip. 

Length Of female, 8-10 mm. (5/16-3/8 of 
an inch) ; male, 7-8 mm. (1/4-5/16 of an inch.) 

The eggs are oval, 65-80 microns in length 
by 30-40 microns in breadth. 

The worm is parasitic in the wall and cavitj' of the aboniasum of 
cattle. 

2. Nem^todirus filicollis (Strongylus filicollis). Fig. 143. Tricho- 
strongylinse (p. 268). — This is a white hair-lilve worm, very thin in front, 
thicker behind. The cuticle has eighteen longitudinal ridges. The 
bursa of the male is bilobate; there are two very long and slender spicules 
united by a membrane posteriorly which forms a spatulate enlargement 
at the tip. The \ailva of the female is a transverse slit located about 
one-third of the length of the body from the caudal extremity. At this 
location the body has its maximum thickness which is suddcnh' reduced 




Fig. 143.^ — Xematodirus filicoUis; male in center, female at left. * Vulva. xl5. At 
right, enlarged anterior portion of body. (After Ransom, Bull. No. 127, Bureau An. Ind., 
U. S. Dept. Agr.). 




Fig. 144. — Cooperia oneophora; male at right, female 
at left. * Vulva. .\15. (After Ransom, Bull. No. 127, 
Bureau .\n. Ind., U. S. Dept. .4gr.). 



TRICHOSTRONGYLIN^ 275 

just behind the vulva. The tip of the tail is truncate and bears a short 
bristle-like process. 

Length of female, 10-24 mm. (3/8-15/16 of an inch) ; male, 8-13 mm. 
(5/16-1/2 of an inch). 

The eggs are elongated oval, 110-113 microns in length by 64-70 
microns in breadth; segmented at time of deposition. The further 
develoi^ment is not known. 

The worm is parasitic in the small intestine of cattle, sheep, and goats. 

3. Cooperia oncophora (Strongylus oncophora). Fig. 144. Tricho- 
strongylinse (p. 268). — The head is rounded, without well-marked papil- 
la; mouth cavity small and not well defined. The cuticle in the region of 
the head is transversely striated; cuticle of remainder of body with 14- 
16 longitudinal hues or ridges; cervical papillae absent. The bursa of 
the male, when spread, is large and has two lateral lobes and a small 
median lobe; border of median lobe incised. The spicules are short 
and of comparatively simple structure. The vulva of the female, is in 
the posterior fourth of the body. At the region of the vulva the body is 
much enlarged. The tail is slender with rounded tip; terminal portion 
of tail marked with annular striations. 

Length of female, 6-8 mm. (5/16 of an inch) ; male about the same. 

The eggs are oval, 60-80 microns in length by 30 microns in width. 

Lihabits the small intestine of cattle and sheep. 

Occurrence and Symptoms. — Haemonchus contortus is frequently 
found in the abomasum of cattle. When the infestation is heavj', which 
usually occurs in young pastured animals, they bring about the symp- 
toms of a pernicious anaemia as described in the infestation of sheep. 
The cattle become infected by grazing upon pastures which are contam- 
inated by the droppings of infected sheep, goats, or other infested cattle. 

The sjaiiptoms caused by the presence of Ostertagia ostertagi, or the 
encysted stomach worm, are similar to those produced bj'' Haemonchus 
contortus. It lives in small cysts in the mucosa of the abomasmri and 
is also found free in the contents of this organ. When numerous, they 
cause a catarrhal condition and disturbances of digestion. 

For Post-mortem Appearance, Development, Etiology, Control, and 
Treatment refer to pp. 275-279. 

Gastro-Intestinal Strongylosis. Post-Mortem Appearance 

Examination of the contents of the abomasum and duodenum from 
an animal which has been heavily infested with stomach strongyles 
will reveal undulating movements of the fluid produced by the active 
wrigghng about of the worms. Large numlDers will also he found deeply 
adhering to the mucosa which will show the lesions of a subacute or 
chronic catarrh. Further than this, the pernicious anaemia is evidenced 



276 PARASITES OF THE DOMESTIC ANI^L\LS 

in the paleness of the body tissues, edematous swelhngs, exudate into 
the serous cavities, and cachexia. 

Where Ostertagia ostertagi are present in the abomasum of cattle they 
will be found both free in the stomach contents and embedded in the 
subepithelial tissue of the mucosa in small round cysts about the size 
of a pin-head or shghth' larger. When numerous, the same lessions are 
shown as in the attack upon the nuicosa of a hea\y invasion with Ha-mon- 
chus contortus. 

Gastro-Intestixal Strongylosis. Development and Etiology 

The eggs of Hccmonchus contortus passed in the feces of the host will 
hatch in a variable time according to the conditions of temperature and 
moisture. When these are favorable it may occur in a few hours, while, 
under more adverse conditions, it may take several daj-s or weeks. 
Dryness or a freezing temperature kills the embryos and newly hatched 
larvaj in a short time. Upon hatching the larva feeds upon the fecal 
matter with which it is surroimded. Later it becomes enveloped by a 
chitinous sheath, in this condition probably receiving nourishment 
from food material stored within its body. At this stage the larva can 
survive freezing and drying for long periods and is motile at temperatures 
above 40° F., becoming more active with increase in temperature. Where 
there is sufficient moisture, as from dew or rain, it crawls upon a blade 
of grass or other vegetation and gradually makes its way to a position 
well removed from the ground. In this position it is taken up by the 
grazing ruminant host and, reaching the abomasum, becomes mature in 
two to four weeks. If the eggs or newl\' hatched larvae are ingested 
they apparentl}^ do not undergo further development. It seems, there- 
fore, that only the ensheathed larvae are infective. 

Control. — As stated in the foregoing, moisture favors the develop- 
ment of the embryos, while dryness kills them at their early stages. 
High jiasture ground, therefore, with good natural drainage greatly 
reduces the chances of the larva? reaching the infective stage. Further- 
more, larviE which have become infective are more motile in the presence 
of moisture such as is supplied by the heavy dews and fogs occurring 
over low land; crawling, then, out upon the wet blades of grass, the 
worms are more likely to be taken up by the grazing animals. 

If the temperature remains constantly at aliout 95° F. the infective 
larval stage is reached in three to four days after the eggs have passed 
from the body of the host. At 70° F. one to two weeks are required, 
while three to four weeks are necessary at about 50° F. At temperatures 
below 40° F. the eggs arc dormant and the larvse remain inactive. Under 
the usual climatic conditions of the northern part of the United States, 
therefore, there is little possibility of new infection from placing in- 



TRICHOSTRONGYLIN^ 277 

fected and noninfected animals together in clean fields from the first 
of November until March. 

During the warmer months the best means of controlling the parasite 
seems to be bj^ the rotation of pastures, keepiag each pasture free from 
sheep and cattle for at least a year, by which tune the larvae will be dead. 
As to this method Ransom (U. S. B. A. I., Cir. No. 102) suggests the 
following: "Infested and nonmfested sheep which have been kept to- 
gether in clean fields from November to March or later, according to 
weather, if moved then to another clean field may remain there nearly 
the entire month of April before there is danger of infection. From the 
first of Maj- on through the summer the pastures become infectious much 
more quickly after infested sheep are placed upon them, and during 
May it would be necessary to move the sheep at the end of every two 
weeks, ia June at the end of every ten days, and in July and August at 
the end of each week, in order to prevent the noninfected sheep from 
becoming infected from the worms present in the rest of the flock. 
After the first of September the period may again be lengthened." 

The difficulties and inconveniences of this method consist in the num- 
ber of small pastures and subdivisions of pastures which it requires; 
furthermore, it miposes hmitations upon the size of the flock. It is, 
however, probably the most effective system thus far devised for the 
eradication of this parasite. 

Where it can be conveniently practiced, it is a good precautionary 
measure to burn over the pastures in the early spring or fall. This will 
destroy most of the eggs and larvse which are lodged upon the grass or 
upon the ground. 

Treatment. — Experiences recorded with the use of drugs for the 
expulsion of stomach worms are somewhat varied. The success attained 
by such treatment has not equaled expectations based upon experiments 
made with the agents upon worms outside of the body of a host. It is 
probable that this is mainly due to the fact that drugs administered to 
ruminants by the mouth do not pass directly to the abomasrmi, but must 
first mix with the ingesta of the rumen and reticulum, passing from the 
latter by way of the omasum to the abomasmn and intestine. Hence, 
before reaching the worms the drug become sufficiently diluted or mixed 
with the bulk}^ ingesta to greatly reduce its effectiveness. Treatment 
for the expulsion of Hcemonchus contortus gives better promise for success 
than that for the smaller stomach strongyles, as Ostertagia ostertagi, 
owing to the protected position of the latter within the mucosa. 

Animals which are to be treated should be taken up in the afternoon 
of the day previous to treatment and all food withheld from them for 
eighteen to twenty-two hours. The remedy should be given the following 
morning either with a long-necked bottle or, better, with a drenching 
tube consisting of about three feet of one-half inch rubber tubing with 



278 PARASITES OF THE DOMESTIC ANIMALS 

a funnel inserted at one end and a four to six inch piece of metal tubing 
inserted in the other end, the metal tube to be placed in the animal's 
mouth between the molar teeth. The funnel may be held b.v an assistant 
or fastened to a post while receiving the liquid, the flow of which may be 
controlled by pinching the rubber tube near the insertion of the metal 
piece. The dosage for each sheep should be carefullj' measured accord- 
ing to age, and care taken to lower the head at once upon entrance of 
the liquid into the laryn.x, this often a result of holding the head too high 
and indicated by coughing. 

Among the remedies used for the expulsion of stomach worms may 
be mentioned (1) copper sulfate, (2) gasoline, and (3) coal-tar creosote. 
An objection to the last named is its variable composition, the substance 
not infrequently sold under the name of coal-tar creosote being quite 
unreliable for the purpose here considered. Copper sulfate has received 
high recommendation and is extensively used in the sheep flocks of 
South Africa. It may be prepared and given as follows: 

Dissolve 1/4 of a pound (avoirdupois) of clear blue crystals of copper 
sulfate in one pint of boiling water, having first crushed the crystals in 
a mortar to a fine powder. In making the solution use a porcelain or 
enamel-ware vessel as the bluestone will corrode most metals. Add to 
this solution enough cold water to make it up to three gallons, using 
non-metallic receptacles. This will make an approximate one per cent, 
solution, and, allowing for waste, will be enough for the treatment of 
about one hundred adult sheep. 

The dosage is to be graded according to age as follows : 

Lambs 3 months to 1 year old 5 drams to 1 1/2 oz. (20-50 cc). 

Sheep over 1 year old 2 to 3 oz. (64 to 96 cc). 

Calves " 3 to 4 oz. (96 to 128 cc). 

Yearling cattle 6 oz. (192 cc). 

The animals should receive no water at any time during the day they 
are dosed. 

Where the stomach worm exists in a flock, it has been suggested as a 
•control measure to give 50 cc of a one per cent, solution of copper 
sulfate eveiy month or so except during the winter in climates where 
the winter is freezing. 

Gasoline has afforded a convenient remedy, but, for reasons which 
need not be gone into here, the commercial gasoline of the present time 
is unsuitable for this purpose. Under such conditions only the official 
purified gasoline (benzinum purificatum, U. S. P.) should be used. At 
best, however, gasoline is probably less satisfactory for the purpose 
than copper sulfate; furthermore, to be effectual, the gasoline treatment 
must be repeated upon three consecutive days. 

In the preparation for the administi-ation of gasoline withhold water 



TRICHOSTRONGYLINiE 279 

as well as feed. The following morning give the gasoline in milk, linseed 
oil, or flaxseed tea, mixing the dose for each animal according to age as 
follows: 

Lambs 2 drams (8 cc.)- 

Sheep 4 drams (16 cc). 

Calves 4 drams (16 cc). 

Yearling cattie 1 oz. (32 cc). 

Three hours later allow feed and water. At night again confine the 
animals without feed and water. The next morning give the second 
dose, the third morning the third dose, the treatment before and after 
dosing being the same in each case. Gasoline should not be given in 
water, nor should it be given soon after the animals have taken water. 

Coal-tar creosote may be given in solution of one per cent, strength. 
The solution is made by shaking together one ounce of coal-tar creosote 
and ninety-nine ounces (6 pints and 3 ounces) of water. The doses of 
this as recommended bj^ Stiles are as follows: 

Lambs 4 to 12 months old 2 to 4 ounces 

Yearling sheep and above 3 to 5 ounces 

Calves 3 to 8 months old 5 to 10 ounces 

Yearling steers 1 pint 

Two-year-olds and above 1 quart 

If a good quaUty of coal-tar creosote is used, good results may be 
obtained from a single dose of this one per cent, solution. 

Other remedies, such as lysol and arsenic, have been recommended 
by various authors, but probably the most effectual will come within 
those which have been particularly mentioned. 

The treatment should be administered to the entire herd, since an- 
imals which may be but lightly infested will remain a source of reinfec- 
tion to others. 

The general condition of the animals should be built up and main- 
tained by a generous supply of nourishing food and they should receive 
a plentiful supply of salt. 



CHAPTER XXIII 

NEMATODA. SUBFAMILY III. STRONGYLIN^ 

Worms of the Large and Small Intestines; Other Strongyles 

These worms are parasitic in the digestive tract, rarely in the respi- 
ratory organs. The buccal capsule is present. The bursa of the male 
is well developed and has one or two dorsal rays and two lateral ray 
systems of six raj's each. There are two spicules. The vulva of the 
female is usuallj- posterior to the middle of the body, but ma^^ be anterior 
to the middle. There are two ovaries. 

The eggs are segmented at the time they are deposited. The embryos 
are rhabditiform. The development, so far as known, is direct. In 
some forms the development is complex, involving a nodular phase or 
larval migration. 

Based mainly upon the formation of the bursal rays and the location 
of the vulva, the Strongj-lina; haxe been grouped by Eailliet and Henry 
into five tribes, as follows : 

Tribe I. CEsophagostomese 

Tribe II. Strongylese (Ankylostomea;) 

Tribe III. Bunostomeae 

Tribe IV. Cylicostomeae 

Tribe Y. Syngamea; 

I. (Esophagostomeae. Strongyhnse (p. 280). — The bursa of the male 
has two lateral lobes united by a smaller median lobe. In each lateral 
lobe there are six rays. The raj' of the median lobe divides into two 
main branches, each of which again divides into two. The vulva of 
the female is situated a short distance in front of the anus; uteri diver- 
gent. The tribe includes three genera, as follows: 

Genus I. Qisophagostomimi 
Genus II. Chabertia (Sclerostomum) 
Genus III. Agriostonumi 

II. Strongyleae. Strongylinae (p. 280). — The ventral and latero- 
ventral lays of the lateral bursal lobes are close together and parallel. 
The medio-lateral and postero-lateral rays are not close together and 
parallel. The dorsal ray ends in tridigitate terminations. The vulva 
of the female is situated in the posterior third of the bod}'; uteri diver- 
gent. The tribe includes four genera, as follows: 

Genus I. Strongj-lus 

Genus II. Ankylostoma 

Genus III. Uncinaria 

Genus IV. Characostomum 



STRONGYLINJE 281 

III. Bunostomeae. 8trongylin£e (p. 280). — The ventral and latero- 
ventral raA's of the bursal lobes are close together and parallel. The 
medio-lateral and postero-lateral rays are not close together and are 
not parallel. The dorsal ray ends in a bifurcation. The vulva of the 
female is situated in the middle of the body or a little anterior to the 
middle; uteri divergent. The tribe includes four genera, as follows: 

Genus I. Bunostomum 
Genus II. Gaigeria 
Genus III. Bathmostomum 
Genus IV. Grammocephalus 

IV. Cylicostomese. Strongyhnse (p. 280). — The ventral and latero- 
ventral rays of the bursal lobes are close together and parallel. The 
medio-lateral and postero-lateral rays are not close together and parallel. 
The dorsal and externo-dorsal rays originate separately. The vulva 
of the female is situated close to the anus; uteri convergent. The tribe 
includes four genera, as follows: 

Genus I. Cylicostomum 
Genus II. OEsophagodontus 
Genus III. Gyalocephalus 
Genus IV. Triodontophorus 

V. Syngamese. Strongylinse (p. 280). — The bursa is obliquely trun- 
cated. The anterior and middle rays are cleft, the posterior tridigitate. 
The vulva of the female is situated in the anterior quarter of the body; 
uteri divergent. The tribe includes one genus — Syngamus. 

Nodular Strongylosis of the Sheep and Goat. ffisoPHAGOSTO- 

MIASIS 

1. CEsophagostomuin columbianum. Fig. 145. Strongyhnse (p. 
280). — The thickness of the body is nearly uniform over its greater 
portion; attenuated toward ends. The anterior portion is usually 
curved in the form of a hook. The cuticle surrounding the mouth is 
inflated to form a collar which has almost the shape of a hemisphere. 
Six circum-oral papillee penetrate this mouth collar. In front of the 
middle of the esophagus there is a transverse groove with accompanying 
cuticular fold extending around the body to the lateral lines. There are 
two cervical papillje in front of the middle of the esophagus. Posterior 
to the cervical groove are two lateral membranes which extend well 
back along the lateral lines. The bursa of the male has two lateral lobes 
united by a small median lobe. The spicules are 7.50-850 microns in 
length, slender and pointed. The vulva of the female is naked, trans- 
versely elongated, and situated a short distance in front of the anus. 

The length of the female is 14-18 mm. (9/16-11/16 of an inch) ; male, 
12-15 mm. (1/2-19/32 of an inch). 



sse 



PARASITES OF THE DOMESTIC ANIJVLiLS 



Fig. 145. — QSsophagostomum columbianum; male 
at left, female at right. * Vulva, x.5. (.\fter Ran- 
som, Bull. No. 127, Bureau An. Ind., U. S. Dept. 
Agr.). 




Fig. 146. — Oi.'iophagostomum col- 
umbianum. Anterior extremity, 
^■entral view, — enlarged: c. g., eer- 
I'ical groove; c. p., cer^^cal papilla; 
es., esophagus; int., intestine; 1. m., 
lateral membrane; 1. p., lateral cir- 
cumoral papilla; m. c., mouth collar; 
n. r., nerve ring. (After Ransom, 
Bull. No. 127, Bureau An. Ind., 
U. S. Dept. Agr.). 



148. Strongyliiiffi (p. 280). 



The eggs are oval, 65-75 microns in 
length by 40-45 microns in breadth. 
Segmentation occurs while they are within 
the uterus. 

The freed embrvos measure 230 mi- 
crons in length. 

Parasitic in the large intestine of the 
sheep and goat. 

2. (Esophagostomum venulosum. Fig 
— The thickness of the bod,\' is nearly uniform over its greater portion, 
attenuated toward ends. The anterior end is usually straight. The 
height of the cuticular collar alDout the mouth is about one-third of its 
diameter. The cuticle of the neck is inflated between the mouth collar 
and the cervical groove. The lateral membranes extend well back but 
are very narrow. The bursa of the male has two lateral lobes united by a 
small median lobe. The spicules are 1.1-1.5 mm. long. The ■vailva of 
the female is naked and located just in front of the anus. From a short 
distance in front of the vulva the body tapers, terminating in a sharply 
pointed tip. 

The female is 18-24 mm. (23/32-15/16 of an inch) in length; male, 
12-16 mm. (15/32-5/8 of an inch). 

The eggs are oval, 90 microns in length by 55 microns in breadth. 



STRONGYLINiE 



283 




Fig. 147. — CEsophagosto- 
mum columbianum. En- 
larged bursa of male viewed 
from right side: d, dorsal 
ray; e. 1., externo-lateral 
ray; 1. v., latero-ventral 
ray; m. I., medic-lateral 
ray; p. 1., postero-Iateral 
ray; v. v., ventro-ventral 
ray. (After Ransom, BuU. 
No. 127, Bureau An. Ind., 
U. S. Dept. Agr.). 




.\i 



Fig. 150. 



Fig. 148.— CEsopha- 
gostomum venulosum ; 
male at right, female 
at left. * Vulva. x5. 
(After Ransom, Bull. 
No. 127, Bureau An. 
Ind., V. S. Dept. Agr.). 



Fig. 150. — CEsopha- 
gostomum venulosum. 
Enlarged bursa of male 
viewed from right side: 
d., dorsal ray; e. d., ex- 
terno-dorsal .ray; e. 1., 
externo-lateral raj'; m. 
1., medio-lateral ray; 
p. 1., postero-Iateral ray; 
sp., spicules; v. v., ven- 
tro-ventral ray. (After 
Ransom, BuU. No. 127. 
Bureau An. Ind., U. S. 
Dept. Agr.). 




Fig. 149. — CEsopha- 
gostomum veuidosum. 
Anterior portion of 
body — enlarged, ventral 
view: c. g., cervical 
groove; c. i, cervical in- 
flation; c. p., cervical 
papilla; es., esophagus; 
int., intestine; 1. m., 
lateral membrane; 1. p., 
lateral circumoral pa- 
pula; m. c, mouth col- 
lar; n. r., nerve ring. 
(After Ransom, Bull. 
No. 127, Bureau An. 
Ind., U. S. Dept. Agr.) 



Parasitic in the large intestine, more rarely in the small intestine, of 
the sheep and goat. The species has been collected in Europe and in the 
United States. It is much less common in this countiy than (Esophagos- 
tomimi columhianum. 

Occurrence and Development. — Nodular disease of the intestines 
of sheep caused by QSsophagosotomimi columbianum is common in the 



284 PARASITES OF THE DOMESTIC ANIjVL^LS 

United States. The nodules are due to the larvte which live embedded in 
the connective tissue of the submocosa, to which they at once penetrate 
after being taken up by the host. According to Mannotel, after six to 
seven months of development in this location, they pass to the intes- 
tinal lumen where they become sexually mature and the female, after cop- 
ulation, deposits her eggs. The eggs pass from the host animal with the 
feces and promptly' hatch if they meet with favorable conditions of heat 
and moisture. The further development outside of a host is not known. 

Natin-al infection probably takes place b^' food and water from wet 
marshy i")astures. If it occurs during August and September the larvaj 
will pass from the nodules into the intestinal lumen during March and 
April, here attaining maturity and copulating in July and August. 

Post-mortem Appearance. — The nodules are most commonlj- found 
in the wall of the cecum and colon, but they may occur in the small 
intestine and at times on the hver and other abdominal organs. They 
may be isolated, but are frequently massed in hundreds and thousands. 
In size they vary from that of a pinhead to that of a pea, or they may 
be considerably larger. Their color varies from blackish in the smaller 
ones to grayish white in the larger. The connective tissue capsule of 
the nodule is thick, and, as the nodule increases in size, it becomes filled 
with a greenish cheesy or purulent material, later becoming calcareous. 
Only the younger nodules contain the larvae. 

Symptoms. — Light infestations, with the presence of a few nodules, 
are not , as a rule, accompanied by perceptible s\nnptoms, the condition 
in such cases being ob.served onlv after slaughtering. Relative to their 
degree, heavier invasions may be accompanied by diarrhea without a 
considerable loss of condition, or the diarrhea may be uncontrollable and 
accomi)anied by progressive emaciation and anaemia. Such cases usually 
terminal e fatally after a course of two or three months, the animal 
succumbing in a state of coma. The effect of the invasion will depend 
considerably upon the age and vitality of the animals infested. 

Importance. — The fact that many slaughtered sheep that were ap- 
parently perfectly healthy show these nodules tends to lead to the im- 
pres.sion that they are of little importance and has perhaps caused them 
to be overlooked as a primary cause of death. Cases of nodular disease 
submitted to the laboratory of the Pennsylvania Bureau of Ani- 
mal Industry indicate that the disease may assume an enzootic char- 
acter of severe type occasioning numerous losses. Usually where 
there is high mortality there is heavy infestation with large areas of 
massed nodules, though there are several factors which render this un- 
necessar.y to a fatal termination. Lighter invasions may have this 
result when by worms with a relatively high degree of virulence; when 
the invaded animal has a low degree of resistance, or when other worms 
are present to contribute to the morbid effect. Furthermore, these 



STRONGYLIN^ 285 

worms may infect the blood and lymph with organisms which cause 
other diseases through acting as direct carriers in penetrating the in- 
testinal wall, or bj^ the wounds which they create affording portals of 
entrance. In such cases a comparatively slight infestation with OEsopha- 
gostomum would be sufficient for what might prove a fatal secondary'- 
effect. 

Treatment. — No effective curative treatment is known. Preventive 
measures consist in keeping the sheep from low wet areas. Where the 
disease is prevalent, lambs may be protected from serious infestation 
by placing them in a drj'' uncontaminated lot and feeding and watering 
them from racks and troughs sufficiently elevated that the contents 
cannot be soiled by droppings from the nursing ewes. 

Nodular Strongylosis of Cattle. CEsophagostomiasis 

(Esophagostomum radiatum ((E. infiatum). Fig. 151. Stron- 
gylinse (p. 280). — The thickness of the body is nearly uniform over its 
greater portion; attenuated toward ends. The anterior portion is 
usuallj^ curved in the form of a hook. The cuticular inflation about the 
mouth (mouth collar) is disk-like, its height a little more than one- 
fourth of its diameter. The mouth capsule is bordered by a circle of 
numerous small triangular denticles. The cervical groove and fold are 
well developed and the cuticle between it and the mouth collar is in- 
flated. This inflation has a slight constriction at about one-third of the 
distance from the cervical groove to the mouth collar. The lateral 
membranes begin at the cervical groove and extend well back along the 
bod}^: near their beginning are two cervical papillae. The bursa of the 
male has two lateral lobes united by a small median lobe ; spicules 700- 
800 microns in length. The \'xilva of the female is transverseh^ elongated 
upon an eminence located just in front of the anus. From the \ailva the 
body rapidly tapers, terminating in a tip which is usually somewhat 
bent in a ventral direction. 

The female is 16-20 mm. (5/8-3/4 of an inch) in length; male, 14-16 
mm. (9/16-5/8 of an inch). 

The eggs are oval, 75-80 microns in length by 38-43 microns in 
breadth. Their segmentation occurs within the body of the female. 

Parasitic in the small and large intestines of cattle. 

While the nodular larval stage of CEsophagostomum columhianum of 
sheep is usually found in the large intestine, that of CEsophagostomum 
radiatum of cattle is often found in the small intestine, the nodules 
usually occurring in the terminal portion with involvement of the region 
of the ileo-cecal valve and the cecum. 

In other respects .what has been said as to nodular disease of sheep 
will, in its essentials, apply to that of cattle. 



28(i 



PARASITES OF THE DOMESTIC ANIMALS 





Fig. 151. — OSsophagostomum 
radiatum; male at right, female 
at left. * Vulva. x5. (After Ran- 
som, Bull. No. 127, Bureau An. 
Ind., U. S. Dept. Agr.). 



Fig. 152. — CEsophagostomum 
radiatum. Enlarged anterior por- . 
tion of body, ventral view: c. a ., 
annular groove surrounding cervical 
inflation of cuticle; c. g., cervical 
groove; c. i., cervical inflation; c. p., 
cervical papilla; e. p., excretory pore; 
es., esophagus; int., intestine; 1. m., 
lateral membrane; m. c, mouth 
collar; n. r., nerve ring. (After Ran- 
som, Bull. No. 127, Bureau An. Ind., 
U. S. Dept. Agr.). 




Fig. 153. — CEsophagostomum radiatum. Enlarged 
bursa of male, viewed from left side: d., dorsal ray; 
d. h., dorsal projection of trunk of lateral rays at base 
of postero-lateral ray; e. d., externo-dorsal ray; e. 1., 
externo-lateral ray; 1. t., trunk of lateral rays; 1. v , 
latero-ventral ray; m. 1., medio-lateral ray; p. 1., postero- 
lateral ray; t. d., terminal branch of dorsal ray; v. v., 
ventro-ventral ray. (After Ransom, Bull. No 127, Bu- 
reau An. Ind., U. S. Dept. Agr.). 



Fig. 153. 



STRONGYLIN^ 



287 



Nodular Strongylosis op the Hog. Q^sophagostomiasis 

(Esophagostomum subulatum (CE. dentatum). Strongylinse (p. 
280). — The body is straight and attenuated at both extremities. The 
circular mouth is surrounded bj' a horny ring furnished with a crown of 
converging bristles. Upon a cutaneous ridge surrounding the crown of 
bristles are six papillae. There are no lateral membranes. The bursa of 
the male has two lateral lobes united bj' a small median lobe; spicules 
slender. The vulva of the female is just in front of the anus and is sur- 
rounded by a prominent ring. 

The female is 12-15 mm. (1/2-9/16 of an inch) in length; male, 8-12 
nun. (5/16-1/2 an inch). 

The eggs are oval, 60-80 microns in length by 35-45 microns in 
breadth. 

This species is found in submucous nodules and in the lumen of the 
large intestine of the hog. Considerable numbers may be present with- 
out causing serious disturb- 
ance. If the infestation is 
unusually heavy — especially 
if associated with the thorn- 
headed worm — there may be 
diarrhea, loss of appetite, 
and general unthrift. Such 
cases may be given treatment 
as recommended for other 
roundworms of the intestines 
of the hog. 

Strongylosis of the Large 
Intestine of the Sheep 
AND Goat 

Chabertia ovina (Sclero- 
stomum h5rpostomuni). Fig. 
154. Strongylinse (p. 280).— 
The bod}^ is almost uniform 
in thickness.v The head is 
slightly globular and is ob- 
licjuely truncated anteriorh^, 
the mouth facing antero-ventrall}'. The buccal capsule is large ; border 
of mouth armed with a double crown of small triangular denticles. Lo- 
cated ventrally, just in front of the excretory pore, is a short transverse 
cervical groove. The bursa of the male is short and has an obliquely 
cut-off appearance; spicules long and slender. The vulva of the female 





Fig. 154. — Chabertia ovina; male at right, female 
at left. * Vulva. x5. (After Ransom, Bull. No. 
127, Bureau An. Ind., U. S. Dept. Agr.). 



288 PARASITES OF THE DOMESTIC ANIMALS 

is situated a little in front of the anus. From in front of the vulva the 
body gradually attenuates, the tail terminating behind the anus in a 
sharply pointed tip which is bent dorsally. 

The female is 17-20 mm. (11/16-3/4 of an inch) in length; male, 13- 
14 mm. (1/2 an inch). 

The eggs are oval, 90-100 microns in length by 50 microns in breadth. 
They are segmented within the body of the female. The eggs have 
similar characters to those of other sclerostomes, and it is probable that 
the evolution external to a host is the same. 

Occurrence. — Strongylosis of the large intestine of sheep due to this 
species is probably more prevalent in Europe than in the United States. 
In reference to the species, Hutyra and Marek state that it is often 
found in the colon of sheep, goats, and deer, inducing in some cases 
intestinal hemorrhage and diarrhea followed by anaemia and emaciation 
which may cause considerable loss among the young animals. 

Neveu-Lemaire speaks of strongylosis of the large intestine of sheep 
as at times ravaging certain flocks in the form of an epizootic. 

Ransom, in United States Bureau of Animal Industry, Bulletin No. 127 
(1911), refers to Chabertia ovina as follows: "This species appears to be 
comparatively harmless. Its food consists of the vegetable material in 
the contents of the large intestine. The buccal capsule is commonty 
found filled with such material."- 

Stkoxgylosis or the Ixte.stixes of the Horse. Sclerostomiasis 

1. Strongylus equinus (St. armatus; Sclerostomum equinum). 
Fig. 15.5. Strongylinae (p. 280), — The body is straight, rigid, and fineh- 
striated transversely; color gray or grayish brown, or 
it may be shaded with red according to the amount 
of ingested blood. The mouth is distended by several 
chitinous rings the innermost of which are provided 
with an armature of fine teeth, while the outermost 
ha\-e six papilliE. The buccal capsule has three teeth 
at its base. The bursa of the male has two lateral 
lobes between which is a smaller median lobe; spicules 
long and slender. The \ailva of the female is located 
near the posterior thii-d of the body. The tail is obtuse. 
The length of the female varies from 20-55 mm. (3/4 
to 2 3,16 inches) ; that of the male from 18 to 35 mm. 

Fig 155— Stron ^^^^^^ ^° ^ ^'^ inches). 

gylus°eqJinus'/malc The eggs are oval, 92 microns in length by 54 mi- 
at right, female at crons in lireadth. Segmentation commences at the 
left. - natural size ^|,^ ^f ^j^pjj. fipposition. The hatched embrvos meas- 

(drawn from speci- .... 

mens). ure 340-500 nucrons m length. 



STRONGYLIN^ 289 

2. Strongylus edentatus (Sclerostomum edentatum). Strongylinae 
(p. 280). — The head is globular. The buccal capsule is goblet-like, and 
teeth are absent. The bursa of the male is similar to that of Strongylus 
equinus. The vulva of the female is near the posterior third of the body. 

The female is 33-36 mm. (1 5/16-1 7/16 inches) in length; male, 23- 
25 mm. (7/8-1 inch). 

The eggs are oval and in dimensions about as in Strongylus equinus. 

As adults these worms are parasitic in the cecum and colon of the 
horse; as larvae in the abdominal and thoracic organs. 

3. Strongylus vulgaris (Sclerostomum vulgare). Strongyhnje (p. 
280) . — The buccal capsule is shallow and has a smgle tooth at its base, 
prominent projections causing the tooth to appear as two. The bursa 
of the male has three lobes, the median one overlapped by the two 
lateral. The vulva of the female is near the posterior third of the body. 

The female is 24 mm. (15/16 of an inch) in length; male, 15 mm. 
(5/8 of an inch). 

The eggs are as in the preceding species. 

Parasitic as adults in the cecum and colon and in immature stages in 
the mesenteric blood vessels of the horse. 

4. Cylicostomum tetracanthum (Sclerostomum tetracanthum) . 
Strongylinffi (p. 280). — A white or reddish white worm, attenuated 
anteriorly, the mouth surrounded by a cuticular fold. The buccal 
capsule is armed with a crown of triangular teeth. The vulva of the 
female is just anterior to the anus. 

The female is 10-18 mm. (3/8-11/16 of an inch) in length; male, 8- 
12 mm. (5/16-1/2 an inch). 

The eggs are oval, 100 microns inlength bj'- 47 microns in breadth. 

Parasitic in the cecum and colon of the horse. 

Development. — The worms causing sclerostomiasis of the horse 
were formerly grouped under the name Strongylus arniatus. According 
to Looss (1902) it is the immature stages of the species Strongylus vul- 
garis (Looss, 1900) which are concerned in the production of verminous 
anevnysms in the mesenteric arteries of the horse. M. Neveu-Lemaire 
(Parasitologic des Animaux Domestiques, 1912) describes the worm 
responsible for these lesions under the name Strongylus equinus. 

This worm when mature lives in the cecum and colon where it firmly 
attaches to the mucosa bj' its buccal armature. In its aganrous state it is 
found in submucous c.vsts of these organs and in aneurysms of the 
mesenteric arterJ^ According to the investigations of Railliet the eggs, 
which are deposited in the cecum and colon and expelled with the feces, 
may develop in a few days if thej' meet with moisture at a temperature 
of i2° to 25° C. (53° to 77° F.). The hatched embryos, if they continue 
amid favorable conditions, grow, molt, and acquire a great Autalit.v. It 
is at this stage that they are ingested by the equine host with the drink- 



290 PARASITES OF THE DOMESTIC ANIMALS 

iiifi' water or perhaps with green forage. Eeaching the intestines, they 
penetrate tlie mucosa from which probably' the majority of them reach 
tiie circulatory system where they become lodged in the visceral arteries, 
as the trunk of the great mesenteric. After a variable time in this 
location they again enter the blood stream and, reaching the cecum, 
oecome encysted in the submocosa where their development proceeds. 
Within the cyst they possess a buccal capsule and a caudal bursa, but 
the generative organs are not as yet developed. 

I'inall>- they pass to the lumen of the liowel where they attach to the 
nmcosa and acquire all the characters of the adult. Copulation then 
takes place, the eggs are deposited, and a new generation repeats the cycle. 

Symptoms. — The symptoms brought about by the presence of these 
worms — a condition generally known under the name of sclerostomiasis — 
are not characteristic and vary according to the location of the parasites. 
The jircsence of the adults upon the mucosa of the cecum, even in con- 
siderable numbers, rarely causes serious disturbance, diarrhea and 
occasional attacks of colic resulting in exceptional cases. 

Sclerostomiasis produced by the larvae is of a much more serious 
nature.- Their most frequent location in this state is in the large arteries 
where they l)ring about the formation of verminous aneurysms, usually 
at the origin of the great mesenteric. Fragments of the clot within the 
ancin\vsni may be carried by the blood to form emboli in the arterial 
ramifications leading to the intestines, that portion of the intestine 
svipplied by an artery in which an embolus is lodged being deprived of its 
normal supi)ly of blood. As a result there is suspension of secretion and 
peristaltic ino\-ements in this section, the walls of a portion of which 
become dark and tumified with the presence of hemorrhagic infarct. 
One or more portions of the intestine may be thus affected, the arrested 
contents fermenting and producing an abundance of gas, while in the 
healthy portions of the intestines there are abnormally energetic con- 
tractions which cause a severe enteralgia and may lead to invagination, 
displacement, and even rupture. The rupture may be of, the paralyzed 
intestine, or it may be of the stomach or diaphragm, brought about by 
the accunnilation of gas generated from the stagnated and fermenting 
intestinal contents, the violent movements of the animal often con- 
tributing toward this termination. 

Post-mortem Appearance. — The adult worms are fixed to the 
mucosa, usually that of the cecum, where they nourish from the blood of 
their host and produce at their ])oint of attachment a small dark prom- 
inence. Innnature worms may be found in submucous nodules of the 
cecum, or of both the cecum and colon. These nodules vary in size from 
that of a pinhead to that of a hazelnut and contain a small quantity of 
pus or sero-purulent material in which the worm, if present, is rolled up. 
The worms escape from the nodules by a central orifice to the lumen of 



STRONGYLIN.E 291 

.the intestine where they attach and are sexually mature, the sexes often 
being found coupled in this location. Before their intranodular existence 
the larval worms live in the blood-vascular system, having gained this 
location through the intestinal wall immediately after their ingestion. 
It is at this stage that they produce the aneurysms as found in the vis- 
ceral trunks of the posterior aorta. These aneurysms are usuallj'- some- 
what elongate, with tunica media much thickened, and with fibrm 
deposit upon the intima, on which a number of reddish tinted strongyls 
are likely to be fixed. The aneurysm may, however, be entirely free 
from worms, in which case they have probably passed with the blood- 
current to the intestinal wall. 

Where death has occurred from thrombo-embolic colic due to ver- 
minous aneurysm, the most prominent alterations found are those which 
have already been described in reference to this complication. The 
intestines are usually much distended by gas, or, if rupture has occurred, 
this, with more or less intestinal contents, will be in the abdominal 
cavity. Extensive darkly discolored areas are usually observed in the 
intestinal walls, and there are likely to be evidences of degeneration if 
the course of the attack has been sufficiently prolonged. Owing to the 
great engorgment of the mesenteric vessels, it is often difficult, without 
the most searching examination, to discover the location of the embolus. 
Rarely the immediate cause of death may be found to have been due to 
rupture of the aneurysm and internal hemorrhage. 

Treatment. — For the strongyles in the intestine the same treatment 
may be employed as has been recommended for the ascarids, though, 
owing to the firm attachment of the former to the mucosa, their expul- 
sion is difficult. Oil of turpentine has been recommended as particu- 
larly valuable. It may be given in two to four ounce doses in oil. 

In prophylaxis clean water is a main factor. This should be filtered or 
quite pure and free from drainage contamination. 

Strongylosis of the Intestine of the Dog and Cat. 
Ankylostomiasis 

1. Ankylostoma canina (Dochmius trigonocephalus ; Uncinaria tri- 
gonocephala ; U. canina) . Fig. 156. StrongjdinEe (p. 280). — The body 
is whitish in color and slender ; slightly enlarged at the anterior extremity. 
On the ventral surface of the buccal capsule are two chitinous plates, 
each having three recurving teeth. The biu'sa of the male is three-lobed, 
two lai'ge lateral and a small median. There are two long and slender 
spicules. The vulva of the female is situated near the posterior third 
of the body. 

The female is 10-20 mm. (3/8-3/4 of an inch) in length; male, 9-12 
mm. (11/32-1/2 an inch). 



292 PARASITES OF THE DOMESTIC ANIMALS 

The eggs are oval, 74-84 microns in length bj' 48-54 microns in 
breadth. 

Parasitic in the small intestine of the tlog and cat. 

2. Uncinaria stenocephala (Dochmius stenocephalus ; Ankylosto- 
mum stenocephalum I . Strongylinte (p. 280). — The body is very- 
slender, and the anterior extremity' is much narrower than in the pre- 
ceding species, being somewhat attenuated. The buccal 
capsule is conical and has two pairs of small teeth on the 
ventral side. The bursa of the male is similar to that of the 
]3receding species. The vulva of the female is situated near 
the posterior third of the body. 

Fig. 156— The female is 8-10 mm. (5/16-3/8 of an inch) in length; 
Ankylostoma male, 6-8 mm. (1/4-5/16 of an inch). 

matc^atrigiit ^^^ ^^gs are oval, 63-76 microns in length by 32-38 
female at left niicrons in breadth. 

(drawn frnm Parasitic ill the small intestine of the dog. There is no 
specimens . ^^ythej^tJc report of its occurrence in this countrj'. 

Occurrence and Development. — Ankylostomiasis (dochmiasis; un- 
cinariasis) is a severe affection of dogs caused l^y the presence of Ankylo- 
stoma canina. The condition is analogous to ankylostomiasis or hook- 
worm disease of man, caused by the species Ankylostoma duodenale. 

The worms fix themselves to the mucosa of the small intestine where 
they extract blood. Hunting dogs confined in kennels are those which 
most often suffer, especialh' if their quarters are damp. Cats are not 
often affected. 

The development of the parasite is rapid. The eggs are segmented 
within the body of the female and, when expelled to moist earth, develop 
embryos in three to six daj-s. These become encysted and, probably 
through the medimii of contaminated water, reach the intestine of the 
dog where they mature. 

Post-morten Appearance. — Necropsies upon dogs which have died 
in the advanced stages of ankylostomiasis show the alterations of 
anaemia and cachexia. The mucosa of the small intestine is thickened 
and marked by numerous hemorrhagic areas. Small ulcerations are 
present as a result of the irritation from the attachment of the worms, 
and the intestinal contents may be hemorrhagic. 

Symptoms. — The sj'mptoms are those of anaemia, debility, and 
emaciation. There is depression and indifference, and hunting dogs 
lose their zest. The skin becomes dry and scaly and the coat harsh 
and lusterless. The legs swell intermittently at first, later the edema 
is greater in extent and becomes permanent. There is a muco-purulent 
discharge from the nostrils and this may be streaked with blood. Later 
there may be attacks of nasal hemorrhage. There is at first constipation, 
later a dysenteric diarrhea. Emaciation and general debility progress, 



STRONGYLIN^ 



293 



and the sjanptoms are finally terminated bj' death in a state of coma or 
it ma,v be in convulsions. 

Treatment. — As the disease usually attacks hunting packs in ken- 
nels, and there is constant reinfection, treatment is, as a rule, not suc- 
cessful. It is most important that care be exercised as to cleanliness of 
the kennel. Where possible, the sick should be removed to other quar- 
ters. Water and food should be given from buckets or troughs which 
are thoroughlj^ flushed out after each meal, and the yards should be 
kept free from pools and mud. As medicinal treatment, the usual 
vermifuges recommended for dogs may be tried. 

Other Strongylinae. — Two other strongyhnes occasionally found in 
sheep and cattle maj' be mentioned. 

1. Bunostomum trigonocephalum (Uncinaria cernua; Dochmius 
cemuus). Strongylinae (p. 280). — Yellowish or reddish in color; 
cuticle transversely striated. The 
buccal capsule has a long dorsal tooth 
projecting forward. The mouth is 
surrounded by six papillae; cephahc 
extremity curved dorsall}^ The 
vulva of the female is near the middle 
of the body. 

The female is 20-28 mm. (3/4-1 1/8 
inch) in length; male, 15-18 mm. 
(5/8-11/16 of an inch). 

Parasitic in the small intestine of 
•ruminants, particularlj' sheep and 
goats. 

2. Bunostomum phlebotomum 
(Uncinaria radiata ; Dochmius radi- 
atus). Fig. 157. Strongylinae (p. 
280).— Dark in color. The dorsal 
buccal tooth is short; two ventral 
buccal teeth and two subventral 
buccal teeth or lancets. The cephalic 
extremitj' is curved. 

The female is 24-28 mm. (15/16-1 1/8 inch) in length; male, 10-16 mm. 
(3/8-5/8 of an inch). 
Parasitic in the small intestine of cattle. 





Fig. 157. — Bunostomum phlebotomum; 
male at right, female at left. * Vulva. 
x5. (After Ransom, Bull. No. 127, Bu- 
reau An. Ind., U. S. Dept. Agr.). 



Thacheal Strongylosis of Chickens. Syngamosis 

Two species of strongylines invade the trachea and bronclii of fowl, — 
Syngamus trachealis and Sijn. bronchialis. The last named is somewhat 
the larger and inhalaits the air passages of water fowl. 



294 PARASITES OF THE DOMESTIC ANIMALS 

Syngamus. Strongylinae (p. 280). — Members of this genus have a 
slender body of reddish color. The month is surrounded by a strong 
chitinous capsule. The female is much larger than the male and is 
usually found with the male firmly attached at the \ailva which is sit- 
uated near the anterior quarter of the body. This permanent coupling 
gives to the pair a forked appearance from which the worm has derived 
its common name of "forked worm" (Fig. 158). The attachment of 
male and female is less constant with the species Syn. hronchialis. 

The female of Syngamus trachealis is 5-20 mm. (3/16-3/4) of an inch 
in length; male, 2-6 mm. (1/16-1/4 of an inch). 

The eggs are elliptical, measuring 85 microns in length by 50 microns 
in breadth. In the uterus of the female thev undergo a variable degree 
of development, containing when freed a segmented mass or 
a developed embryo. The eggs are not laid Init escape from 
the body by its loipture, which ordinarily occurs from decom- 
position, though, according to Railliet, eggs contained in 
the \-agina may pass through the ^'ulva and from under the 
l)ursa of the male to the outside. 

Occurrence and Development. — The condition produced 
in fowl liy s\-nganii is conimf>nly known in England and the 
United States as gapes. It is widely prevalent, practically 
all of our domestic birds and man.y wild birds, especially 
tadicd at those in captivity, suffering from it. 

maN>)"" "^^ ■'^ jjeculiar feature in the evolution of Hijiigdmus trachealis 
is the fact alr(>ady noted that, due to the covering of the 
vulva by the permanent attachment of the male, the eggs cannot be 
extruded and are only liberated by the rupture or disintegration of the 
mother worm. This may occur within the air passages or after the 
worm ha.s been exjjelled. If the eggs meet with water or moist earth 
the embryos develop and are hatched in .seven to forty days according 
to temperature. Birds may become infested by ingesting eggs or em- 
bryos, often by eating the worms expelled by infested members of the 
flock. From the digestive tract the larvse migrate to the air passages 
where thej' mature. 

Lesions. — The worms are generally found covered with mucus and 
in gieatest number near the division of the trachea into bronchi. The 
mucosa, to which they are firmly fixed by their buccal capsule, exhibits 
at each point of attachment a small ]:)urulent tumor, or there may have 
developed an abscess sufficiently large to obstruct the trachea. The 
number of coupled worms present may be three or four or twenty to 
thirty, the smaller numbers being ciuite sufficient to cause death by 
asphyxiation, though this will lie influenced .somewhat by age and the 
diameter of the trachea. 

Symptoms. — Young birds suffer most from s^^lgamosis, those in 




STRONGYLIN^ 295 

good condition being equallj' susceptible with otliers. A typical symp- 
tom of the affection is a peculiar stretching of the neck accompanied 
by a yawn-like opening of the beak from which movement the disease 
derives its name "gapes." The birds repeatedly shake their heads, 
sneeze, and expel tenacious masses of mucus which ma\' contain one 
or more pairs of the worms. The appetite, at first voracious, diminishes, 
and the birds become dull and inactive with feathers erect and lusterless. 

Emaciation progresses, the mouth is filled with froth^^ saliva, respira- 
tion becomes increasingly difficult, and the animal dies from exhaustion, 
or it may be from asphyxia before such advanced symptoms are reached. 
Recovery is rare in young birds. Older ones sometimes survive if the 
infestation is light. 

Treatment. — A method of treatment commonly practiced is to strip 
a feather of its barbules to within a short distance of its tip and insertmg 
this into the trachea with a rotary movement, attempt to detach and 
elevate the worms. Only such worms as are not firmlj^ fixed to the 
mucosa are removed by this process and, in view of the danger of its 
causing suffocation, it is a questionable procedure unless as an urgent 
palliative measure. 

A better treatment is to give with the food certain substances of strong 
odor eliminated in the respiratory passages and having a deleterious 
effect upon the parasites. As such agents garlic and asafetida have 
been employed with success. According to Neumann, Megnin has had 
good results with a mixture of equal parts of asafetida and powdered 
gentian root incorj^orated in a cake and given in the proportion of eight 
grains per bird each day. 

Another method recommended is the injection into the trachea of 
about fifteen drops of a five to eight per cent, solution of salicylic acid. 
The injection should be made slowly with a small syringe and canula. 

Fumigations with such agents as sulphurous acid or tobacco smoke, 
resorted to by some, involve such risk of accident from suffocation as 
to make their use unadvisable. 

As prevention, affected birds and those apparently healthy should 
be removed to clean and separate quarters and the infested yards 
cleaned and sprinkled with a one to one thousand solution of sulphuric 
acid. The bodies of dead birds are to be buried deeply or burned. 
Food and water should be fresh, given from clean utensils, and not per- 
mitted to stand about. As an aid in prevention the addition of fifteen 
grains of salicylate of soda to the quart of drinking water has been 
recommended. 

The Kidney Worm of the Hog 

Stephanurus dentatus. Strongylidse (p. 255). — This worm is at 
present of somewliat uncertain position in the classification of the 



296 PARASITES OF THE DOMESTIC ANIjVMLS 

strongjdes. The bodj' is thick, cjlindiical, and has a mottled appear- 
ance, due to the intestine and reproductive organs showing through 
the semi-transparent integument. Both extremities are somewhat 
blunted; the mouth terminal with six small teeth. The liursa of the male 
is formed of five tongue-like parts united l)y a membrane; there is but 
one spicule. The olituse caudal extremity of the female is curved; 
^aIlva near the middle of the liody. 

The length of the female is 30-40 mm. (1 3/16-1 9/16 inch); male, 
22-30 nun. (7/8-1 3/16 inch). 

Parasitic in fat surrounding al>dominal viscera, especially that of the 
sublunibar region in the vicinity of the kidneys. 

The kidney-worm is foiuul in hogs of the United States — especially 
those of the South — and in South America, the species being first dis- 
covered in Brazil. Its presence may cause the formation of cysts up 
to the size of a pigeon's egg in the adipose tissue, these on incision usually 
revealing one or two of the worms and a small amount of pus. Rarely 
the worms penetrate the ca{)sule of the kidney or enter the suprarenals. 
Indurated fistulous tracts, liver lesions, and peritoneal effusion have 
been observed as a i-esult of the presence of these parasites, though it 
may be said of them that they rarely cause perceptible disturbance 
unless in unusual locations in the abdominal cavity. 

Due to their location, treatment can be of no value. 



FAMILY VI. EUSTRONGYLID.E 

ErsTKONGYLOSI.S 

This is a condition produced by a giant nematode, — Dioctophyme 
renale (D. visccralis; Eu^trottgyluf< viscerah-'i; Eit. gigas), which is some- 
times met with in the kidney and peritoneal cavity of dogs and other 
domestic animals. It has also been reported in man. 

Dioclophyme Tcnale (Ncmatoda, p. 217) is of somewhat uncertain 
position among the nematodes. It has been conunonly placed with the 
family StrongylidaB, but it does not conform to all of the characteristics 
of this family. Neveu-Lemaire describes the genus Eustrongylus under 
the sejiarate famih' Eustrongylida". 

Tiic worm is the largest of all the nematodes, the female attaining 
a length of one meter (39 inches) and a thickness of a centimeter (3/8 
of an inch); the males a length of forty centimeters (15 inches). The 
body is blood-red in coloi-, somewhat thinner toward the anterior ex- 
tremity than posteriorly. The bursa of the male is collar-like, entire, 
and without rays. Within its base is located the anus. There is a single 
slender spicule (Fig. 1.59). The tail of the female is obtuse. There is a 
single ovary; ■vulva near the mouth. 



EUSTRONGYLIDiE 



297 



The eggs are 64-68 microns in length l:ij' 40-44 microns in width. 
They are brownish in color and have numerous round depressions on 
their surface. They develop in a moist medium. 

The embryos are tapering at the extremities and about 240 microns 
in length b^^ 40 microns in breadth. They have a 
great vitality and may survive within the eggs for 
a year or more. 

Attempts at direct infection have been unsuc- 
cessful. An intermediate host is evidently re- 
quired, and the fact that the worm is found para- 
sitic in the seal and otter points to the probability 
that it lives a portion of its life in a fish. 

The eustrongyle is much more frequent in Car- 
nivora, especially the dog, than in other animals, 
but it is rarelj^ met with. In the Journal of the 
American Veterinary Medical Association, June, 
1917, Hall states that from Riley's and his own 
record of cases reported it appears that this worm 
has been found at least forty or fiftj^ times in the 
United States. How and in what form it finds its 
waj^ into the body of its host is not known. It is 
most frequently found in the pelvis of the kidney 
where it grows to an enormous size, producing a 
purulent inflammation from which destruction of 
the renal tissue follows. Eventually the kidnej' 
becomes a mere thick-walled cyst containing a 
bloody purulent material within which the worm 
is coiled up. But one kidnej^ is invaded, usually 
by a single worm, though in rare cases two have 
been found in the kidney pelvis. The uninfested 
kidney is usually found to have undergone a com- 
pensatory hypertrophj'. The worm has been 
met with in other parts of the urinary organs, as 
in a part or the whole of the ureter and m the 
bladder. Where it is found outside of the urinary 
organs, as in the peritoneal cavity, it is probable 
that it did not reach such location until after 
primary development in the urinar}' passages. 

Symptoms. — The symptoms are not characteristic and in some cases 
may not be observed. Horses and cattle especially are said to show 
little disturbance fi'om the presence of the worm, while dogs, on the 
other hand, suffer severe pain, are restless, and sometimes exhibit a 
lateral curvature of the vertebral column, the concavity' corresponding 
to the affected side. [Nlicturation may be painful and with effort, and 




Fig. 159. — Diocto- 
phj-me renale; male, — 
natural size (after Rail- 
lie t). 



298 PARASITES OF THE DOMESTIC ANIMALS 

the urine may be purulent and liloody. An exact diagnosis can only 
be made in the living animal by finding the characteristic eggs of the 
eustrongjde in the urine. 

In view of the location and size of the worm, treatment is imprac- 
ticable. 



CHAPTER XXIV 

NEMATODA. FAMILY VII. TRICHINELLIDiE 

Nematoda (p. 217). 

The nematodes of this famil_v have a very slender and elongated 
anterior portion of the body, containing only the esophagus. The pos- 
terior portion is more or less enlarged and is occupied by the mtestine 
and reproductive organs. The mouth is rounded and nude. The anus 
is terminal or nearlj^ so. The males have a single testis and but one 
spicule or the spicule may be absent. The females have a single ovaiy. 
The vulva is located at the junction of the smaller with the larger por- 
tion of the bodv. They are oviparous (Trichuris) or ovoi-iviparous 
(Trichinella). 

The worms of this group to be described come under two genera, — 
Trichuris and Trichinella. Of these but one species, — TrichineHa 
spiralis, is of pathologic importance. 

Trichuris ovis (Trichocephalus affinis). Fig. 160. Trichinellidte 
(p. 299). — The esophageal portion of the bodj' is very long and slender; 
the posterior portion, containing the reproductive organs, much thicker. 
The head is sometimes provided with two transparent wing-like en- 
largements. The posterior extremity is more or less blunt and rounded. 
The body is transversely striated. The posterior portion of the body 
of the male is rolled dorsally in a spiral. The spicule is very long, 
measuring 5-7 mm. (7/32-9/32 of an inch) and terminating in a sharp 
point. 

The female is 50-70 mm. (2-2 3/4 inches) in length, the esophageal 
portion constituting about two-thirds of the total length. The male is 
50-80 mm. (2-3 1/8 inches) in length, the esophageal portion in the 
same proportion to the total length as in the female. 

The eggs are lemon-shaped, 70-80 microns long, and have an ojDercular 
plug at each end. 'Development is direct. 

This species is a common parasite in the large intestine of ruminants, 
particularly' the sheep and goat. Leuckart has demonstrated that it 
develops directl.v from the egg without intermediate host and without 
a free living stage. When the eggs are taken into the intestine of the 
ruminant host the em]Dr3-os are freed and attain their adult development 
in about sixteen days. They are usually found attached firmly to the 
nuK'osa, but apiiarpntl\' cause little if any troulile. 

Trichuris crenatus (Trichocephalus crenatus). Trichinellidae (p, 
299). — The esophageal jiortion of the liody is very slender, the posterior 



300 



PARASITES OF THE DOMESTIC ANBIALS 




Fig. Ibl. — Tiichuris ovis. Egg. 
x600. (After Ransom, Bull. No. 127, 
Bureau An. Ind., U. S. Dept. Agr.). 



portion enlarged. The female 
measures 35-50 mm. (1 3/8-2 
inches) in length, the anterior 
slender portion constituting 
about two-thirds of the total 
length. The length of the male 
is 33-40 mm. (1 5/16-1 9/16 
inch), the anterior part about 
five-eighths of the total. 

The eggs are 52-56 microns 
in length. 

The worm lives in the large 
intestine of domestic and wild 
hogs. Infestation occurs as in 
the preceding species. Ap- 
parently little disturbance is 
caused by its presence. 

Trichuris depressiusculus 
(Trichocephalus depressiuscu- 
lus). Trichinellidse (p. 299).— 
The male and female are 45- 
7.') mm. (1 3/4-3 inches) in 
length, the slender esophageal 
portion constituting the ante- 

l-'i(i. 1110. -^Trichuris ovis; male at right, female rior throe-quartCl'S. The spe- 
ticc. Bull. No. 127. Bureau An. Ind., U.S. "PS lesemmes J ncnuris 0116 Ol 

Dept. .\Kr.). ruminants and Tr. dispar of 

man. The spicule of the male 
may reach the length of 10 mm. (3/8 of an inch) and terminates in a 
sharp point. 

The eggs are 70-80 microns in length. The develo]inient is similar 
to that of the preceding species. 

This parasite inhabits the large intestine, usually the cecum, of the 
dog. Eggs taken up by dogs release their embryos within the digestive 
tract where they iittain full development. The worms are often found 




TRICHINELLID^ 



301 



in the cecum of clogs suffering from ankj'lostomiasis, but have an in- 
significant secondary part to Ankylostoma canina as a cause of this 
affection. 

Trichinosis 

Trichinella spiralis (Trichina spiralis). Fig. 162. Trichinellidse 
(p. 299). — A verj' small worm with body somewhat thicker posteriorh', 
but without abruptly demarcated fila- ^ g 

mentous anterior as in the Trichurinae. 
The mouth is round and unarmed. The 
esophageal portion extends to about one- 
half of the length of the body, the esoph- 
agus embedded in a chain of single cells. 
The portion of the bodj^ posterior to the 
esophageal contains the intestine which 
ends in a terminal anus. The single 
testis of the male originates posteriorly 
and extends forward to the esophagus 
where it turns back and becomes the 
seminal vesicle which terminates at the 
anal aperture. The cloaca thus formed 
has on each side of its opening two pro- 
jections which serve to clasp the female, 
the cloaca being extruded in copulation. 
There is no spicule. The single ovarj^ 
of the female begins posteriorly and, ex- 
tendmg forward for a short distance, be- 
comes the uterus. The vulva is about 
one-fifth of the length of the body from 
the anterior end. 

The female is 3-4 mm. (1/8-5/32 of an 
inch) in length; male, 1.4-1.6 mm. (1/16 
of an inch). 

The embryos are developed within the 
uterus and are hatched there bj^ breaking 
through the delicate membrane sur- 
rounding the egg. From the uterus and 
vagina they pass from the body of the 
mother worm through the \'Tilva. The 
hatched embryos are 100-160 microns 
long bj' 9 microns thick, the anterior end 
somewhat thicker than the posterior. 

Parasitic as adults in the small intestine and as lar\-a? in the muscula 
ture of hogs, rats. mice, and other mammals, including man. 




Fig. 162. — Trichinella spiralis; 
male at left, female at right, — 
much enlarged. 



302 



PARASITES OF THE DOMESTIC ANIALA.LS 



Life History. — When flesh contaiiiinfi; encapsulated living trichinee 
is taken into the stomach of a suitable animal, the capsule is digested 
and they are liberated within eighteen to twenty-four hours. The 
larvije then enter the small intestine and are sexually mature in two to 
five days. The females with the males are pressed into the crypts of 
Liebcrkiihn where, a week to ten daj-s after the infection, the female 
deposits living embrj^os. There is at first an equal mmiber of males 
and females in the intestine; later the males gradually disappear, so 
that ten to fourteen da\'S after infection ahuost all of the worms will be 
females. These live five to eight weeks, a single female, according to 
Leuckart, tlepo.siting not less than fifteen hundred embryos; according 
to Braun, the number may reach ten thousand. 

From Lieberkiihn's glands the embryos penetrate the mucosa and, 
reaching the Ij-mphatics, are probably carried to the blood by way of 
the thoracic duct. With the blood they are distributed to various parts 
of the body, passively in greater part, though it is 
probal)le that their ultimate lodgment is influenced 
somewhat by their activity. Embryos deposited by 
capillary lilood in striated nmscle with sarcolenuna 
aro amid conditions favorable to their further develop- 
ment. From the capillaries the trichinsE force their 
way through the sarcolenuna and into the plasma of 
the muscle-fiber, where, at first actively motile, they 
jiass to a state of rest and proceerl to develop into 
the larval stage at which, if ingested, thev may infect 
other animals. 

In about three weeks after the occurrence of the 
infection the larvte in their muscular location have 
attained a length of eight-tenths to one millimeter, 
and their growth is completed. At this time they 
are usually curved in the form of a sickle, later becom- 
ing coiled spirally (Fig. 163), from which characteristic 
they derive their specific name, though they may be 
found in various looped and curved forms. The an- 
terior portion of the larva is now the thinner; the pos- 
terior thicker and rounded at its extremity. 
As a result of this invasion the muscle-fibers undergo certain changes; 
the transverse striation is lost, there is degeneration of the sarcoplasm, 
and the nuclei increase in number and size, each becoming surrounded 
by a granular mass. The irritation to the surrounding tissues cau.sed 
l)y the presence of the parasites results in the formation of cysts which 
enclose the trichinre and are full.v developed at the end of the third 
month. The long axis of the capsule is parallel to that of the muscle- 
fiber. The capsules are usually oval in shape and more or less drawn 




KiG. Hi:J.— Tri- 
cliinctla spiralis. 
Encysted larva in 
muscle (after Leuc- 
kart). 



TRICHINELLIDiE 303 

out at the poles, giving them somewhat the shape of a lemon. Their 
dimensions vaiy with the thickness of their walls. In general, they 
are about four-tenths of a millimeter in length by twenty-five one- 
hundredths of a milluneter in breadth, but their length may be from 
three-tenths to eight-tenths of a millimeter and their breadth from 
two-tenths to four-tenths of a millimeter. After the formation of the 
cysts they are often made more recognizable to the unaided eye by the 
deposition of fat cells immediately around their poles. Within each 
cyst there is usuallj^ one, more rarely two or more, larvae. 

T.^BUL.'VR Review of Life History of Trichinella Spiralis 

Mature Worms. — In intestines of hog, rat, etc. Period of 
I intestinal trichinosis. 

Embiyos. — In intestinal crypts of same. 

Embryos. — In Ijmiph and blood currents after pene- 

I trating intestinal wall. 

Embryos. — Migrating within fibers of voluntary mus- 

I cle. Period of muscular trichinosis. 

Encysted Larvae. — At rest within voluntary muscle- 

I fibers. 

Larvae. — Freed from cysts after ingestion by hog, rat, 

I man, etc. 

Mature Worms. — In intestines of same. 

Degeneration. — After a varying period of time the trichina cyst 
undergoes fatty and calcareous degeneration. In the first there appear 
within the cyst cells small fat granules which rapidlj^ increase in number 
and are soon set free to invade the whole of the cyst. Later there is a 
deposition of carbonate and phosphate of lime, the calcification involving 
the capsule and the tissues of the trichina, though the latter often es- 
capes the process, and perfectly intact trichinae may be found in cysts 
entirely calcified and opaque. 

Calcification of the capsule begins about the seventh month after in- 
fection and is completed in from fifteen to eighteen months, though ex- 
ceptions give to these periods but a general application. Ostertag 
states that completeh^ calcified trichina capsules were found in two 
hogs nine and twelve months old, and, according to the same author, 
Dammann reported a case in which after eleven years the trichina cap- 
sules were not completely calcified and contained trichina still capable 
of producing experimental trichinosis. 

Location. — Encysted trichinae are found in striated muscle in which 
the fibers have a sarcolemma. Thev are not found in the muscle- 



304 PARASITES OF THE DOMESTIC ANIMALS 

fibers of the heart. Certain muscles are pecuharlj^ liable to invasion 
by the parasites, and these in the order of frequency may be listed as 
follows, — ])illars of the diaiihragm, muscles of the larynx and tongue, 
abdominal and intercostal nuiscles, psoas muscles, and nuiscles of the 
back. They are usually found in greatest number toward the extrem- 
ities of the muscles in the neighliorhootl of tendons, a fact probably to 
be accounted for in the arrest offered b_\- these locations to their migra- 
tions. 

The number of cj'sts which an infested individual maj' harbor is 

ca])al)le of reaching an enormously high figiu-e. Neumann states that 

Lcuckart has counted between twelve hundred and fifteen hundred in a 

gram (15.43 grains) of muscle, while Fielder, 

jJ^^^^^H accordmg to the same author, estimated the 

^L^^f^^^^l number found in the body of a young woman 

^^^J^^B^^^Hj as 

1^^^^^^^^^^^ Occurrence. — Adult trichinae are only found 

^^B^^^^^^^ in the intestines, especiall.v the upper part of 

^^l^^^^^i^^m the small intestine, of mammals and birds which 

^^r ^^r have recently eaten fiesh containing the en- 

' I cvsted larva?. In fishes and other cold-blooded 



Fig. 164. — Trichinella vertebrates the trichina cysts are not acted 
spiralis. Cyst in human upon bv the digestive canal and thev pass 

muscle (from micropho- ., i' -xi ^ i /^r ji ■ i' 

tograph b.v Hoedt). through Without change. Or the animals com- 

monly' used for human food only the hog harbors 
muscle trichina Ijy natural infection, and trichinosis of man is usually 
acquii'cd 1 )y coating the trichinosed flesh of this animal. Rats are peculiarly 
susceptibh; to trichina, and probably one of the most frequent sources 
of th(> infection of hogs is by eating trichinous rats. Transmission to 
herbivorous animals, as cattle, sheep, and horses, is difficult. After 
experimental feeding of flesh containing the cysts to these animals 
there is usuall.v a development of intestinal trichinae but no muscle 
trichinse. Intestinal trichinae have been experimentally developed in 
birds, but l)irds do not harbor the encj'sted larvae. 

Onl>' encysted living larvae are capable of producing trichinosis in 
their suitable hosts. Ingested larvae which are unprotected by a CJ^st 
arc destro>'ed in the stomach by the direct action of the gastric juice. 

Symptoms in Hogs. — Symptoms of trichinosis by natural infection 
are rarely observed in hogs, though where a considerable quantity of 
the cysts have been ingested it is probable that such sjanptoms follow, 
their true cause being unrecognized. Feeding experiments have shown 
that after massive infestation intestinal trichinosis is manifested b^' 
the third to the eighth day. There is then depression, loss of apjjetite, 
grinding of the teeth, and a disposition to remain crouched in the 
bedding or to stand about with back arched and abdomen retracted. 



TRICHINELLID.E 305 

A persistent diarrhea follows wtiicli is at first lumpj"-, tlien waterj'- and 
of bad odor. With these sjanptoms there maj^ also be those of colic. 
In general the sjanptoms are those of an entero-peritonitis and they 
continue over several weeks during which time the animal may die. 

In from one to two weeks the larva are penetrating the muscular 
tissue, and muscular trichinosis has set in. The animal now lies upon its 
side, or, if it moves about, it is in a stiff, halting, and painful manner. 
The respiration is superficial, the voice husky, and chewing and swallow- 
ing difficult. 

With the coming to rest and encapsulation of the larvae the animals, 
in most cases, gradually recover. Where there has been exceptionally 
heavy infestation edema may appear in various parts of the boch'; 
such a development is usualh' followed by death. 

Prophylaxis. — Most all cases of infection of man with trichina are 
from eating tricliinosed pork, the swine usually becommg infected by 
eating the trichinous fiesh of other swine or that of affected rats and 
mice. Knowing these facts, prevention is made relatively smiple. 
Places where hogs are kept should be freed from rats, and the flesh of 
animals subject to muscular trichmosis should not be fed to hogs un- 
less it has been thoroughly cooked. Accordmg to Leuckart, trichinte 
are killed at a temperature between 62° and 70° C. (143°-158° F.). 
These degrees of heat must be continued sufficiently to penetrate the 
entire piece of meat, a white or light gray cut surface indicating that the 
cooking has been sufficient. 

Treatment. — Treatment is ineffectual. In the case of such an ex- 
tremely rare occurrence as the early diagnosis of intestinal trichinosis, 
the administration of anthelmintics followed by purgatives might be 
of some value, but the deep location of the mature worms in the crypts 
of the mucosa affords them a high degree of protection against such 
agents. 



CHAPTER XXV 

THE THORN-HEADED WORM. THE LEECHES 

Order II. Acanthocephala. Nemathelminthes (p. 216). — E.ssential 
differences separatiiis; tliis order from the Neniatoda are the absence of 
a digesti\'e tube and the possession of a protractile rostrum provided 
with hooks. The body cavity contains a fluid in which are the sexual 
organs. The sexes are separate. 

One species is of sufficient pathologic importance for consideration. 
This i.s the large intestinal roundworm of the hog, Gigantorhynchus 
hirucliiwceus of the family Gigantorhynchidae, more commonly described 
under the name Echinorhyiichus gigas. 

Gigantorhynchus hirudinaceus ( Echinorhynchus gigas). Fig. 165. 
Acanthocephala (p. 306). — The body is white, cylindrical, transversely 
wrinkled, and often expanded at several points. The rostrum is almost 
globular, retractile, and has five or six rows of l^ackward-curving hooks 
(Fig. 166). The caudal extreiuity is somewhat tapering. The males 
are smaller and thinner than the females and have a bell-shaped caudal 
bur.sa. The caudal extremity of the female is rounded. 

The female is 20-35 cm. (8-13 inches) in length by 4-9 mm. (5/32- 
11/32 of an inch) in breadth. The male is 6-10 cm. (2 3/8^ inches) in 
length and in breadth 3-5 mm. (1/8-7/32 of an inch). 

The eggs are oblong, measuring 87-100 microns. When developed 
they are .surrounded by three envelops. The embryos are formed within 
the body of the female. 

The adult worm is parasitic in the small intestine of the hog; excep- 
tionally it occurs in man. The larva lives encysted in the white grub 
of the Alay-beetle and probably some other invertebrates. 

The eggs of Gigantorhynchus. discharged to the ground with the 
feces of the hog and eaten by the larva of the May-beetle, are hatched 
in the digestive canal, and the eml^ryos, by burrowing through the in- 
testinal wall, find their way into the body-cavitj^ where they become 
encysted. In this state they may continue to live through the larval 
and pupal stages and even after the maturity of the insect. If the hog 
eats the May-beetle in anj' of these stages containing the cyst, the cyst 
wall is digested away and the freed larval worm attaches by its cephalic 
hooks to the intestinal nuicosa whei'e it attains full development. 

Occurrence, Pathogenesis and Symptoms. — The giant intestinal 
worm of the hog is quite common in the United States, especially so in 



THE THORN-HEADED WORM. THE LEECHES 



307 



the southern portion. The implantation of the worms upon the in 
testinal wall by means of their hooked rostrum causes limited inflam- 
matory areas of red or j'ellowish color. The 
tumifaction of the wall causes the serosa to 
be pushed out in the form of nodules which 
may be of yellowish color and somewhat 
tubercular in appearance. Exceptionally it 
has been observed that the parasite has bored 
through the walls of the intestine and given 
rise to a purulent peritonitis. 

As applies to helminthiasis in general, the 
disturbances which these worms produce will 
be in proportion to their number. Pain may 
be evidenced by continual grunting and rest- 
lessness, and there is the general derangement 
of digestion and the unthrift usual to heavy 
invasion of the intestines by worms. Young 
pigs suffer most and, in these particularly, 
there may be muscular twitchings and epilep- 
tiform seizures, such symptoms usually being- 
followed by death. 

Treatment. — Due to the 
firm attachment of the 
worms, little or nothing can 
be accomplished by treat- 
ment. If this is attempted, 

the same remedies may be used as reconnnended for the 
ascai-ids (p. 241). 





Fig. 165. — Gigantorhynchus 
hirudinaceus, — natural size 
(drawn from specimen). 



Fig. 16(3. -^ 
Armed cephalic 
e.xtremity of Gi- 
gantorhynchus hi- 
rudinaceus, — en- 
larged. 



Class II. Annelida 
Coelhelminthes (p. 216). — The annulated worms differ 



from those of the class Nemathelminthes in ha-\ang a 
segmented body cavity with corresponding ringing or 
annulation of the body wall. The earthworm is usually 
taken for type study of the group. 
Order Hirudinea. Annelida (p. 307). — This order includes the 
leeches which differ in many respects from typical annelids. The body 
is flattened dorso-ventrally and lacks the appendages for locomotion 
(setje) characteristic of other forms. Locomotion is accomplished by 
two suckers, one at the posterior end, used only for locomotion and 
attachment, the other surrounding the mouth, used for locomotion 
and attachment and also for sucking the food. In moving from place 
to place the head end is thrust forward and attached by the sucker. 
The hind sucker is then released and brought close to the anterior sucker 



308 



PARASITES OF THE DOMESTIC ANIMALS 



by a looping up of the l^odj^, tlie antei'ior sucker being again advanced 
and the process repeated. The}' can also swim freely b^y snake-like 
movements in the water. The body surface is transversely striated, 
giving the appearance of a large number of segments. The striations, 
however, are in excess of the true segmentation representing the somites, 
the primitive segment rings being divided by secondary striations. 
The alimentarj' canal has a mmiber of paired sac-like protuberances 
var\'ing in number according to species. When the leech gorges itself 
these sacular pockets are filled with blood upon which the animal may 
live for some time before again feeding. The body cavity is reduced by 
the connective tissue and nuisculature to a number of tubular sinuses. 

The leeches are hermaphroditic and copulate reciprocally (cross 
fertilization). As in the earthworms, certain of the somites at the time 
of re])roduction develop into a clitellum which secretes porous cocoons 
in which the eggs ai-e deposited. 

The leeches to be considered come under one family, the Gnathobdel- 
lida>. ^\■hich ha\-e the pharynx provided with three semicircular chitinous 
jjlates or jaws, each armed on its free edge 
with numerous teeth. The Rhynchobdellidse 
are without jaws. This family contains species 
which attack fishes and invertebrates and occa- 
sionally water fowl. 

1. Haeraopis sanguisuga. The horse leech. 
(Fig. 1G7,). Hirudinea (p. :}07).— Dorsally this 
leech is greenish ))rown or sometimes reddish 
in color; ventrally dark gray, reddish gray, or 
black. Generally the bod>' has four to six longi- 
tudinal rows of closel.A^ set dark points which 
may be somewhat indistinct. The body is 
widest in the middle, gradually narrowing an- 
teriorly, and is composed of ninety-five to 
ninety-seven segments. It is rounded dorsally, 
flattened ventrally, soft, viscid, and cajiable of 
great extension and retraction. The oral sucker 
is slightl.v concave, having at its center the 
mouth which is in the form of a three-rayed 
star (Fig. 167). Each of these ray-like slits 
permits the passage of a jaw, the teeth of which wound the mucous 
membrane and thus enable the leech to suck blood while it holds on 
by means of the oral sucker. There are ten indistinct eyes located 
anteriorly on the dorsal surface. The \'ulva is a transverse slit located 
five rings behind the male orifice, or between the twenty-ninth and 
thirtieth rings. 

In fecundation two individuals come together by their ventral sur- 




Fio. 167. — Haemopis san- 
guisuga. Oral sucker of 
same at right. 



THE THORN-HEADED WORM. THE LEECHES 309 

faces in opposite directions, each having the part of male and female. 
After the cross fertilization is accomplished there forms around the part 
of the body where the sexual organs are located a chtellmn which is a 
sort of girdle secreting the capsules with which the eggs become sur- 
rounded. The leeches then bury themselves in damp ground where the 
eggs are deposited and incubation proceeds, this process occupying 
about twenty-eight days. 

2. Hirudo medicinalis. The medicinalleech. Hirudinea (p. 307). — 
This species is a little smaller than the horse leech. The dorsal surface 
is darker than the ventral and is usually marked with six longitudinal 
reddish stripes. The ventral surface is usually olive green and may 
be more or less spotted. 

This leech was once extensively employed in medical practice for the 
abstraction of blood. 

All of the domesticated animals and man are attacked by Hsemopis, 
probably the horse most frequentlj^ The leeches live in ponds and 
springs where the animals are Kkely to drink and are conve3^ed to the 
mouth with the water. Those taken up are usually the young ones, 
these keeping near the surface of the water, while the adults usually 
lie in the mud at the bottom. Having thus gained access to the mucous 
membranes, they fix upon the lips, cheeks, pharynx, or other parts of 
the mouth. They may enter the nasal cavities through the nostrils 
direct, or they may attach to the eyelids. While holding fast in these 
positions by their oral and caudal suckers, the leeches lacerate the 
mucous membrane with their cutting jaws and become gorged with 
blood. They then detach and pass from their host, or thej^ maj^ attach 
to another part of the mucous membrane and renew their feeding. 

The effect of the infestation will depend upon the nmnber of leeches 
present, and this is extremelj'' variable. It is estimated that a single 
leech when engorged will hold about eight cubic centimeters (two drams) 
of blood. The host suffers an additional loss from the fact that there is 
considerable hemorrhage from the wounds after the engorged leeches 
have become detached. Heavy invasions, therefore, are capable of 
bringing about considerable depletion with evidences of ansemia, as 
paleness of visible mucous membranes, edemas, and emaciation. A 
fatal asphyxia may develop from edema of the pharjarx which may be 
contributed to by the mechanical obstruction offered by the leeches in 
this location. 

Treatment. — Where exploration of the mouth or nasal passages 
reveals the presence of leeches, those which are accessible may be re- 
moved by forceps or with the hand wrapped in a towel. Vinegar, or a 
strong solution of conunon salt repeatedly apphed with a view to causing 
them to release their hold, is recommended bj' some, but the effective- 
ness of such treatment can only apply to the leeches with which the liquid 



310 PARASITES OF THE DOIMESTIC ANIMALS 

comes in contact, many of which niaj' be so far hack in the passages as 
not to be reached. 

A method which is probably better than the s,yringe in the applica- 
tion of this treatment consists in firmly attaching a small sponge to 
the end of a probe, such as a piece of rigid rubber tubing. The sponge 
is saturated with salt solution and, preferably with the use of a mouth 
speculimi, passed back over the soft palate and pharynx. In the same 
manner it may be applied deeply into the nasal passages, the tube being 
inserted slowl}' and with a rotarj' movement. 



PART III 
THE PATHOGENIC PROTOZOA . 

CHAPTER XXVI 

PHYLUM IV. PROTOZOA 

This division includes the most primitive organisms belonging to the 
animal kingdom. While some can be detected by sharp eyes as tiny 
swimming specks, most all are so small that thej^ can only be seen with 
the aid of the microscope. The individual animal is constituted by a 
single cell, which, with a difference in development, characteristically 
distinguishes the Protozoa from other animal groups. In most cases 
they live independently of each other, but not rarely a number are 
associated in colonies. Each individual in such a colony is, as a rule, 
physiologically complete, that is, performing within itself all of the 
functions necessary to its life and reproduction. The colonization, 
however, tends to a degree of differentiation and interdependence, and 
in certain cases there are morphological and physiological differences 
an)ong the individuals so grouped, these usually being related primarily 
to the functions of nutrition and reproduction. 

The protozoan colony may be said to differ from the metazoan in that 
each cell of the colony represents an animal which may live unassociated 
with other cells, while in the metazoan the individual is comprised by 
the aggregation of cells among which there is a morphological differentia- 
tion corresponding to special" functions which are distributed among 
adaptively specialized cell-groups; the body-cells are not capable of fi-ee 
existence and they can only live as integral parts of the metazoan. 
The Protozoa being single-celled animals, there is a further fundamental 
difference in their development, since it essentialh' follows that there is 
no formation of germ layers as occurs in all Metazoa. The division or 
budding of the ]Drotozoan cell results directly in a new generation and 
not in the development of germinal tissue layers, though the new cells 
may remain aggregated to form a colony. 

While the Protozoa are referred to as the most simple representati\-es 
of the animal kingdom, they present, nevertheless, considerable differ-- 
ences in form and modification of the cytoplasm, the functions of mo- 
tion, alimentation, excretion, and reproduction lieing performed bj' a 



3U 



PARASITES OF THE DOMESTIC ANIMALS 



much greater specialization in some than in others. While a nucleus is 
not easily demonstrable in certain of the Protozoa, most have one or 
more distinct nuclei, in this, as in other respects, possessing the essential 
parts of a typical cell. 

Ameba. — A simple representative of the Protozoa is the Ameba 
(Fig. 168) which ma.y be found in most any still water, most readily in 
the ooze u])on the bottom or adhering to leaves or other submerged 




Fiu. lOS. — -•Vnieba protcus (after ('rawlcy, from Di)f5fin; Cir. 
No. 194, Bureau .\n. Iiid., U. S. Dcpt. Agr.). 



objects. Search of such material under the low power of the microscope 
will reveal this organism as a minute protoplasmic particle which slowly 
changes its shape and location by a peculiar flowing and extension of 
the cjioplasm at one or more points, forming iri-egular, often finger-like, 
projections, — the pseudojiodia. These may tie withdi'awn or the whole 
substance of the animal may appear to flow into one of the projections; 
by this manner of locomotion it may slowly pass out of the microscopic 
field. Close study of the organism will reveal two distinct regions, an 
.outer hyaline, — the ectoplasm (eetosarc), and a central more granular 
and less transparent part, — the endoplasm (endoisarc). Within the latter 
ma}' be seen the food vacuoles which are rounded or oval, of varying 



PROTOZOA 313 

size, and inclose granules of food material. At intervals clear globules 
may be seen to gradually form within the cytoplasm and then suddenly 
contract and disappear. These are the contractile vacuoles which on 
contracting empty their fluid contents to the exterior. They are rudi- 
mentary cell organs for the elunination of injurious substances and differ 
from the food vacuoles in having a definite place in the cell as well as in 
their approximately constant number. Young amebse usually have 
within the endoplasm a single nucleus but they may early become 
multmucleate. All of the vital functions appear to be under the con- 
trol of the nucleus; experimental removal of the nuclei has shown that 
Protozoa thus treated cannot properly perform their functions and soon 
perish. 

In feeding the ameba merely flows around the object which it is to 
use as food; becoming thus inclosed in the cytoplasm the nutritive 
elements are digested and assimilated. Circulation is limited to the 
streaming movements of the cytoplasm, and respu-ation is carried on bj^ 
absorption of oxj^gen from the surrounding water. 

Reproduction in ameba is by fission or budding. Before division of 
the cell changes occur in the nucleus involving a separation of the 
nuclear parts with the formation of two distinct nuclei. These separate 
and during the process the cell constricts, finally dividing completelj^ 
with each part inclosing one of the new nuclei. In some cases the cell 
becomes spherical and secretes a protecting membrane around itself 
before division; the outer membrane becomes hard and adapted to re- 
sist drying and extremes of temperature, the organism assuming in this 
condition a resting or enc3^sted stage. Encysted individuals usualh'' 
divide into more than two; there may be four, eight, or even hundreds 
of small amebse resulting from the reproductive process. In multi- 
nucleate forms it frequentlj^ happens that the division is into as many 
parts as there are nuclei. 

Parasitism of the Protozoa 

In 1881 Laverau, a physician in the French army, distinctively 
directed attention to the Protozoa as a cause of disease in animals bj^ 
his discovery that the cause of malaria in man is a protozoan which, 
entering the red blood cells, destroj^s them and in this way causes the 
anremia characteristic of the disease. Later it was demonstrated that 
this malarial organism is transmitted bj^ a mosquito and that this is the 
only way that the disease can be acquired. This discovery served to 
indicate lines of research looking to insects and other arthropods as 
essential carriers of other forms of pathogenic Protozoa, in wliich field 
much has alread.y been accomplished. 

Theobald Smith, in 1892, found that Texas fever of cattle is caused 



314 PARASITES OF THE DOMESTIC ANIMALS 

l)y a protozoan which, though not identical with it, is allied to the 
malarial parasite, and, like it, enters and destroys the red blood cells. 
In this case the infecting organism has been found to be conveyed from 
animal to animal by a certain species of tick {Margaropus annulatus, 
p. 144), and it is now known that the presence of the tick is essential to 
such transmission. 

Trypanosomes were first studied in mammalian blood In' Lewi.s in 
1877, who observed them in the blood of a rat. Three years later 
Trypanosoma evansi was studied as the cause of surra, a disease of horses 
of Asiatic countries, the transmitting agent of which is thought to be a 
blood sucking fly (Tabanus, p. 332). 

Bruce, in 1894, demonstrated that a trypanosome (Trypanosoma 
hrucei) was the specific organism causing the fatal nagana or tsetse 
flj' disease of horses and other domestic anunals of Africa. He showed 
conclusively that blood-sucking invertebrates, mainly the tsetse flies 
(Glossina, p. 44), are responsible for its transmission from the blood of 
wilTl inunune to the blood of susceptible domesticated animals. 

The relationship of the tsetse fly to human trypanosomiasis was shown 
in nuich the same way as that followed in the researches of Bruce. 
African sleeping sickness of man was originally confined to the West 
Coast; it has spread eastward and is now a serious menace to the develop- 
ment of Central Africa. In 1002 the infecting organism of this fatal 
disease was discovered to be a trypanosome [Trypanosoma gambiense) 
cari'ied from host to host mainly by a tsetse fly. Students of jirotozool- 
ogy have since shown that mosquitoes, lice, and leeches may carrj' 
trj'panosomes, and that piercing flies, therefore, ma.v not alone be 
responsible foi- the spread of the diseases which are caused by these 
Protozoa. 

The instances above cited will serve to direct attention to the im- 
jiortance of the Protozoa from the viewpoint of their pathogenicity both 
in its economic relation and as regards disease in man. Up to the present 
time the Protozoa as disease-pioducing organisms have not received 
the attention in the United States that has been given them by inves- 
tigators in Africa and Europe. This is prol)abl>' due to the fact that, 
though this country is not free from pathogenic trypanosomes, it has 
thus far escaped the ravages of the trypanosomiases of Africa, Asia, 
and South America, to which countries sleeping sickness, kala-azar 
(leishmaniasis), nagana, surra, and mal de caderas have to the present 
time confined their plague. A slight accjuaintance with the subject, 
however, is sufficient to dispel a feeling of security based upon the 
erroneous impression that these diseases are restricted to tropical 
countries or that their sjiread depends upon the presence of a certain 
kind o£ fly. It has already been noted that the African trypanosomiases 
maj' not depenfl wholly upon the tsetse flies for their existence and 



PROTOZOA 315 

spread; surra and mal de caderas certainly do not, as these are diseases 
of Asia and South America respectively, and tsetse flies are not found in 
either of these countries. There is, in fact, no reason to doubt that any 
blood-sucking fly can transmit trypanosomes from the blood of one 
host to that of another. In view of this the horse and stable flies, so 
common in North America, would, in the presence of trypanosomiasis, 
amply supply the means for its spread. 

In recent years important advances have been made in the study 
of the role of arthropods in the spread of disease. Common knowledge 
as to its powers for carrying bacterial infection has condemned the 
fly to the swat, but it is as essential hosts, and not as purely mechanical 
carriers, that these invertebrates furnish the greatest field for research. 
Much has already been accomplished in working out the life histories 
of the parasites of insects and ticks, including parasites which have no 
apparent connection with diseases of higher animals, for these, po- 
tentially at least, may not be so harmless to higher animals as may at 
first appear. Change of habitat, as from one part of the body to another 
in the same host, or from a host of one species to that of another, _ fre- 
quently leads to great alteration in the mode of life of an organism 
which, relatively harmless in the insect, may in the vertebrate evolute 
into more harmful parasitism with the development of pathogenicity. 
The newer a parasite is to the animal harboring it, the less it is in har- 
mony with its environment. Protozoa which produce acute forms of 
disease have less adaptation to their environment than those producing 
a chronic type of malady. This discord between parasite and host is 
manifested by acute disturbances which may result in the death of the 
infected animal. Such parasitic diseases of a chronic course are usually 
correlated with a greater degree of adaptation of the parasite to its 
host and also with acquired resisting powers of the host to the specific 
action of the parasite. 

The scdle of evolution through the saprophytic, parasitic, and patho- 
genic is thus exhibited by certain groups. The Spirochetida, long, 
delicate Protozoa with a corkscrew-formed bodj', may be found as in- 
habitants of the body-cavities, of normal mucous surfaces, of inflamed 
mucous surfaces, as parasites which have penetrated the tissue, and as 
blood parasites. This series is sufficient to show how parasitism may 
evolute by various gradations from harmless commensalism to distinct 
parasitism and pathogenicity. When the habit of living in inflamed or 
ulcerated tissues is reached the power of penetrating health}- tissues 
soon follows which, with the multiplication of the spirochetes in such 
situations, causes destruction of invaded tissue and local disturbances. 
The products of this tissue destruction, together with those coming from 
the dead bodies of the parasites, form to.xins which, getting into the 
blood, produce the general toxemic symptoms. The final stage of 



316 PARASITES OF THE DOMESTIC ANIMALS 

malignant parasitism is reached when the spirochetes acquire the habit 
of hving in the blood. In this ease it is evident that, except under cer- 
tain conditions of contact, the transfer from host to host cannot be direct, 
but that the intervention of an intermediate host is necessary. This must 
be a blood-sucking invertebrate, and, in certain known cases of spiroche- 
tosis of domestic animals, has been found to be a tick, as the tick Argas 
minialus, the carrier of Spirocheta galUnarum which causes a spiroche- 
tosis in fowls, and the cattle tick Boophilus decoloratus, the inter- 
mediate host of Spirocheta theileri, the cause of a disease among South 
American cattle. 

The malaria parasites afford stud\' in the evolution of pathogenicity 
of other Protozoa. These organisms indicate in their morphology and 
development that they are closely allied to the Coccidia, which are 
protozoan cell jiarasites attacking and entering tissue cells, especially 
epithelium, of arthropods and vertebrates. There is little doubt that 
the malaria parasites were originall.v Coccidia of insects that, with 
change of habitat, developed increased pathogenicity toward the new 
host. 

Granting this, we have, then, in the malaria parasites an example 
of the evolution of disease in the past, while disease in the making is 
evidenced to-day more especially in the case of certain parasitic flag- 
ellates of the genus Herpetomonas. 

The introduction of herpetomads into vertebrates by the latter 
swallowing infected insects, or by the waj' of wounds of the skin, has 
been shown to result in pathogenic effects in the vertebrate host. A 
series of experiments extending over some six years (Fantham and 
Porter, Journal of Parasitology, June, 1916) have shown that certain 
herpetomads normally parasitic in insects, when introduced into ver- 
tebrates will produce a condition resembling kala-azar, an infectious 
disease of man common in certain regions of India, China, and coimtries 
bordering on the Mediterranean, caused by the herpetomad Leishinania 
(Herpetomonas) donovnni. The sjinptoms developed and the mor- 
]ihology of the pai'asite found in the vertebrate host show that here at 
least are examples of kala-azar in process of evolution. 

Plate III. — Evolution of the Parasite of Kala-.\zar. Figs. 1 to 5. Parasites of 
k'lla-azar. 1. Isolated parasites of different forms in the spleen and liver. 2. Division 
forms from liver and bone marrow. .3. Mononuclear spleen cells containing the parasites. 
4. Groups of parasites. .5. Phagocytosis of a parasite by a polynuclear leucocyte. Figs. 
6 to 15. Parasites from cultures. 6. First changes in the parasites. The protoplasm has 
increased in bulk and the nucleus has become larger. 7. Further increase in size. Vacuoli- 
zation of the protoplasm. S. Division of the enlarged parasite. 9. Evolution of the 
flagella. 10. Small piriform parasite showing flagellum. 11. Further development and 
division of the parasite. 12. Flagellated trypanosome-like form. 13. 14. Flagellated 
forms dividing by a splitting-off of a portion of the protoplasm. 15. Narrow flagellated 
parasites which have arisen by the type of division shown in Figs. 13 and 14. (.\fter Craw- 
lev, from Mense's "Handbuch," after Leishman, Cir. No. 194, Bu. An. Ind., U. S. Dept. 
Agr.). 















o^r 3 



^ :j^ ^ 






f) 




^^^^^^m^"^ 




318 PARASITES OF THE DOMESTIC ANIMALS 

A brief review of these conclusions, drawn from the results of ex- 
perimental research, will be sufficient to direct attention, not only to 
the powers which insects have as carriers of disease, but to their poten- 
tial ]")owers in the making nf disease as well. 

Methods of Reproduction. — Sexual and asexual methods of repro- 
duction alternate in free forms of Protozoa, but the asexual method is 
usually limited to simple division or building. Parasitic forms, on the 
other hand, have acquired a more prolific means of nuiltiplication, the 
simple division and building being replaced by asexual spore formation 
as exemplified among the Sporozoa. In the parasitic Protozoa, there- 
fore, two kinds of spores may be present, the one occurring asexually 
during the vegetative life in the host and giving rise to auto-infection 
in the same host, the other sexual, occurring at the end of the vegetative 
life of the parasite, piepaiing its germs to withstand the unfavoral)le 
conditions of an external cnviroinnent, and giving rise to infection of 
new hosts. 

The asexual method of nuiltiplication, taking ]ilace during the veg- 
etative life in the host, is termed schizogony or schizogenesis, while the 
term sporogony or sporogenesis has been given to reproduction by the 
sexual method. The first is sometimes referred to as the multiplicative, 
the second as the propagative cycle. 

Life History of the Malaria Organisms. — With a view to an ele- 
mental conception of these reproductive and infective processes in the 
Sporozoa, the life history of the organisms producing malaria in man 
.affords a clear example for study. 

Malaria was the first of the human diseases in which it was proved 
that a i)rotozoan is the direct cause, and by 1901 the disease was as 
thoroughly understood as perhaps any other due to a germ. The malaria 
parasites belong with the genus Plasmodium, so named from their early 
supposed resemblance to some of the plasmodia-forming fungi. The.v 
are u.sually considered under three forms with which three well-marked 
types of malaria are associated. These may be briefly .summarized as 
follows: 

1. Flaniiiudluni rirax. — Cause of tertian fever; paroxysms occur every 
forty-eight hours; incul)ati<)n peiiod about two weeks. Temperate cli- 
mates, al.so in tro])ics and subtropics. 

2. Plasmodium falciparum (P. proecox). — Cause of estivo-autumnal 
fever; pai'oxysms every twenty-four hours; incubation period usually 
from ten to twelve days. Tropics and subtropics. 

3. Plasmodium malaria. — Cause of (juartan fever; jiaroxysms every 
seventy-two hours; incubation ])eriod about three weeks. Tropics and 
subtropics. 

Two distinct cycles are involved in the life history of the malaria 
organisms. The first takes place in the blood of the human patient and 



PROTOZOA 319 

is known as the asexaial or schizogonic cycle, during which the plasmodia 
iniiltiply by the asexual method or schizogony. The second occurs in 
the body of a mosquito and is the sexual or sporogonic cycle, involving- 
reproduction by the sexual method or sporogony. A third phase is to 
he I'ecognized during which the female gametocytes sporulate without 
■ fertilization. This is referred to as the parthenogenetic cycle. It is 
passed within the body of the human host and explains the recurrence 
of malaria after more or less prolonged periods of latency. 

The Schizogonic or Asexual Cycle. — The asexual cycle begins with 
the infection of the human blood with the sporozoites by the bite of a 
moscjuito of the genus Anopheles (p. 26). The sporozoite is spindle- 
shaped and on entering the blood at once penetrates a red corpuscle 
where it takes a rmg-like form, referred to as the signet ring stage. Liv- 
ing at the expense of the corpuscle, the organism grows rapidly until it 
more or less fills the corpUscle. At this stage it is known as the schizont, 
which is the period of its ameboid movement and highest vegetative ac- 
tivity. As the schizont matures its nucleus breaks up into a number of 
daughter nuclei, each becoming surrounded Ijy a spherical portion of 
protoplasm to form a small reproductive element, — the merozoite, or 
asexually formed spore. Finally the corpuscle is broken down and the 
swarm of merozoites is liberated in the blood-plasma. Coming from the 
same original brood, the parasites all sporulate and become liberated in 
the blood at the same time; this results in the constantly increasing 
number of merozoites being liberated at stated intervals with corre- 
sponding intervals of paro.xysni in the host. The general toxic effect 
upon the malaria patient is contributed to by the accumulated waste 
products of the parasite's metabolism which pass into the plasma with 
the liberation of the merozoites. Each liberated merozoite now enters 
another corpuscle, and the asexual cycle is repeated in from twenty- 
four to seventy-two hours according to tjie species of the infecting or- 
ganism. ' 

This process of multiplication may continue for an indefinite time 
or, by analogy with other parasitic Protozoa, until the vitality is ex- 
hausted. Asexual merozoites are greatly in the majority, but certain of 
them are potentially sexual and require a longer time to fully develop 
into males and females when they are known as male and female game- 
tocytes. ^Up to this time they are still intracorpuscular and, in the 
estivo-autumnal or pernicious type of fever, appear as large crescents. 
The female orescent (macrogametocyte) has numerous pigment gran- 
ules collected in the center; the male (microgametocyte) is the mother 
cell of the male reproductive elements (microgametes). The nucleus 
of the male cell divides into a number of daughter nuclei which migrate 
to the periphery and become the nuclei of the flagelhform microgametes. 
These bodies are constantly in the blood after the first few paroxysms. 



320 PARASITES OF THE DOMESTIC ANIMALS 

If the blood is now drawn l)y an anopheline mosquito further changes 
take place. 

The Sporogonic or Sexual Cycle. — In the intestine of the mosquito 
the female gametocyte undergoes certain nuclear changes prepai'atory 
to fertilization; the cell becomes romided or oval in form, and is now 
known as the macrogamete. From the male gametoc.yte there are ex- 
truded from thi'ec to six flagelliform filaments corresponding in number 
to the peripherally disposed daughter nuclei. These filaments detach 
from the mother cell to become the actively motile niicrogametes, which 
are analogous to the spermatozoa of higher animals. Thus the flag- 
ellated parent boch' may be referred to as a microgamctoblast, produc- 
ing the male sexual elements or niicrogametes. 

Fertilization of the macrogamete is brought about by its penetration 
by one of the microgametes. The fertilized macrogamete now becomes 
the ookinete or zygote, in which stage it passes b}' a vermiform move- 
ment into and through the epithelium of the mosquitoe's mid-intestine 
and comes to rest just beneath the outer lining membrane. Here it 
rapidly grows, the nucleus divides, and by the third to the fifth day it has 
formed a cyst in which there are many nuclei, each to become the nucleus 
of a minute body, — the sporoblast. The sporoblasts, by division, form a 
number of germs, — the sporozoites, spindle-shaped, nucleated bodies 
which are mature after a period of ten to fourteen days in the body of 
the mosfiuito. On reaching maturity, the sporozoites are liberated into 
the liody cavit}' of the insect where they are carried aliout by the body 
fluids, collecting eventually in the salivary glands. From here they 
pass to the piercing proboscis from which, with the next bite of the mo.s- 
quito, many may pass into the blood of another hvnnan victim to begin 
the asexual cycle. 



Pl.\te I\'. — Life Cycle of the Malaria Parasite. 1. Free sporozoite, either in 
salivary glands of the mosquito or in blood of man. 2. Penetration of the sporozoite into a 
red blood corpuscle. .3 to 6. Growth of trophozoite. 7, 8. Division of trophozoite which 
brings about destruction of the blood corpuscle and the release of the merozoites in the 
blood stream. The free merozoites then enter new blood corpuscles, and this cycle may 
be repeated man.v times. Finall.v, however, the sexual cycle is initiated as follows: 9a to 
12a. Growth and differentiation of female cell. 9b to 12b. Growth and differentiation of 
male cell. 1.3a, 1.3b. The male and female cells are swallowed by a mosquito. 14a. Matu- 
ration of female cell. 14b. Formation of microgametes. 15b. Free microgamete. 16. 
Fertilization. 17. Ookinete. 18. 19, 20. The ookinete attacks and penetrates a cell of 
the intestine of the mosquito, and passes completel.v through the epithelium, coming to 
rest in the peri-intcstinal tissue. (There is not. in life, the reduction in size indicated by 
the figure.) 21 to 25. .Stages in the development of the cyst and formation of the sporozo- 
ites. 26. Migration of the sporozoites. 27. Sporozoites in the sali\'ary glands of the 
mosquito. 13c to 17c. These figures portra.v the cycle which is supposed to account for 
cases where malaria is latent for a longer or shorter period. Ordinarily, unless removed by 
a mosquito, the differentiated male and female cells (12a and 12b) die, but under certain 
conditions the latter ma.v continue to live in the blood, to give rise to a renewal of the 
disease, (.\fter Crawley, from Mense's "Handbuch," after Grassi and Schaudinn, Cir. 
No. 194, BiL .\n, Ind., U. S. Dcpt. -Agr.). 




23 22 



3-22 PARASITES OF THE DO:\IESTIC -\NIMALS 

In the parthenogenetic phase, which occurs in the human host, the 
female ganietocj'te sporulates without fertihzation. After months of 
latency these spores may pass into the blood current and enter the 
corpuscles, bringing about a recurrence of malaria after its apparent 
cure. 

It should be noted in the sexual cycle that the formation of the spo- 
roblasts is similar to the formation of corresponding reproductive cen- 
ters of the Coccidia, which pass a portion of their cj'cle external to a host 
and which arc elsewhere referred to (p. 337). The sporoblasts of the Plas- 
modia, however, differ from those of the Coccidia in having no protect- 
ing memlirane or capusle, in the absence of which ])rotection, the spo- 
rozoites arc unfitted for existence outside the body of a host animal. 

Classification. — According to their mode of life, Calkins divides the 
jjaiasitic Protozoa into the following groups. The arrangement is not 
a natural one and is merely for descriptive purposes: 

1. Enterozoic. — Living in the lumen of the digestive tract. 

2. Ca?lozoic. — Living in the coelomic cavities of the body. 

3. Cj'tozoic. — Living throughout the vegetative period as intracel- 
lular parasites. 

4. Caryozoic. — Passing into the cell to find lodgment in the cell nu- 
cleus. 

0. Hematozoic. — Living in the blood plasma. 

In some cases the parasite may pass through a number of these modes 
of life. Thus the plasmodia of malaria are hematozoic in the blood 
current, cj-tozoic in the blood corpuscles, enterozoic in the digestive 
tract of the mosciuito, and coelozoic when they pass as sporozoites into 
the body cavity of this insect. 

In the arrangement of the classification of the Protozoa which follows, 
only those groups containing species of parasitic importance are given. 

Cl.\ssific.\tiox of P.\r.\sites of the Phylum Protozoa 

Phylum IV. Protozoa. P. 311. 
Class A. Khizopoda. P. 324. 
Order 1. Lobosa. P. 324. 
(ienus and Species: 

Amel)a meleagridis. Host, turkey. P. 325. 
Entameba histolytica. Host, man. P. 326. 
E. coli. Host, man. P. 326. 
Class B. Flagellata. P. 326. 
Order 1. Spirochetida. P. 327. 
Genus and Species: 

Spirocheta gallinarum. Host, fowl. P. 327. 
Order 2. Trypanosoniatifla. P. 328. 



PROTOZOA 323 

Genus and Species: 

Trypanosoma theileri. Host, cattle. P. 329. 

T. brucei. Hosts, equines, cattle, etc. P. 330. 

T. evansi. Hosts, equines, camel. P. 332. 

T. equinum. Host, equines. P. 332. 

T. ecjuiperdum. Host, equines. P. 333. 

T. americanum. Host, cattle. P. 336. 

Tn-panoplasma. P. 329. 
Class C. "Sporozoa. P. 336. 
Order 1. Coccidia. P. 337. 
Genus and Species: 

Eimeria stiedse. Host, rabbit. P. 342. 

Diplospora bigemina. Host, dog. P. 342. 

Coccidium zurni. Host, cattle. P. 343. 

Eimeria avium. Host, chicken. P. 34.5. 
Order 2. Hemosporidia. P. 347. 
Genus and Species: 

Piroplasma bigeminum. Hosts, cattle, tick. P. 347. 

Plasmodimii vivax. Hosts, man, mosquito. P. 318. 

PI. falciparum. Hosts, man, mosquito. P. 318. 

PI. malariae. Hosts, man, mosquito. P. 318. 
Order 3. Sarcosporidia. P. 350. 
Genus and Species: 

Sarcocystis miescheriana. Host, pig. P. 351. 

S. tenella. Host, sheep. P. 351. 

S. blanchardi. Host, cattle. P. 351. 

S. bertrami. Host, equines. P. 351. 



CHAPTER XXVII 

THE PROTOZOAN SUBGROUPS. DISEASES DUE TO 
PROTOZOA 

Class I. Rhizopoda. Protozoa (p. 311). 

The Protozoa of this group lack peniianent structures for locomotion 
and nourishment, these functions being performed by the undifferen- 
tiated protojilasni. For tliis reason they are considered to be the lowest 
in position of the Protozoa. The class name — Rhizopoda — has ref- 
erence to the extension of the cytoplasm in root-hke processes or feet, — 
the pseudopodia or false feet. It is in this manner that the annual flows 
over and engulfs its food, the movements serving for locomotion as well. 
This type of locomotion is known as ameboid, it having been first 
accurately' studied in the Ameba. It differs from that of higher Pro- 
tozoa in that it is not accomplished by constant cell organs, as cilia and 
fiagella. A jiseudopodium is formed when the cytoplasm streams to a 
point of the l)ody, the process extending more or less beyond the gen- 
eral body smface; the bodj' may then be drawn after it or appear 
to flow into it, the protrusion disappearing and new pseudopodia being 
formed at other points. By repetition of this process a slow change 
in the position of the organism occurs, and if particles of nourish- 
ment are encountered in such wandering they are engulfed by 
the cytoplasm within which they become surrounded by a certain 
amount of litiuid, presumably of a digestive nature, to form the food 
vacuole. 

The form of the pseudopodia varies, and this serves as a factor in the 
separation of the rhizopods into different groups. In the Anieba (Fig. 
168) they are thick and finger-like, while in certain other forms they are 
of such delicacy as to appear like fine threads. 

Reproduction in Rhizopoda may be accompanied with the formation 
■of flagellate spores, the ameboid method of motility being exchanged 
for that of the flagellated Protozoa. In this stage the body becomes 
oval and the flagelluin develops at the end containing the nucleus, 
where it persists during the spore stage. 

The parasitic Rhizopoda belong with the order Lobosa which is the 
only one considered here. The characteristics of this group have been 
sufficiently referred to in the description of the type genus Ameba 
(p. 312). There are but few parasitic species known, and these are 
included in the two genera Ameba and Entameba. 



THE PROTOZOAN SUBGROUPS 325 

Infectious Entero-Hepatitis of Turkeys 

This disease — commonly known as blackhead — has been attributed 
to an organism found by Theobald Smith in the necrotic liver of affected 
turkeys and named by him Ameba meleagridis. That this is an ameba, 
however, has been questioned. Certain other investigators consider 
the organism described by Smith as a form in the development of in- 
testinal Coccidia, the acceptance of which conclusion would place the 
disease among the coccidioses. 

The term "blackhead" has been used to designate a number of dis- 
eases of fowls, among which, in addition to entero-hepatitis, are 
cholera, helminthiasis, intestinal coccidiosis, and, in general, any dis- 
ease which may be accompanied by dark discoloration of the comb and 
wattles. 

Symptoms. — It has been shown that entero-hepatitis can be trans- 
mitted directly from diseased to healthy tui-kej^s, natural infection prob- 
ably taking place through food and water contaminated with the 
droppings from the affected animals. At the expiration of the incuba- 
tion period, which is usually within one month, the disease is initiated 
by loss of appetite and a drooping listlessness which is soon followed 
by diarrhea, the fluid discharge being yellowish in color and of exceed- 
ingly offensive odor. Weakness and emaciation have already set in, 
and the comb and wattles show the blackish discoloration from which 
the disea;se takes its name, — blackhead. 

Death usually occurs after a course of from five to eight days. The 
mortality is highest in young animals, among which it is estimated to 
be eighty to ninety per cent. Adults are more likely to recover, though 
usually only after a long period of emaciation during which there may 
be a relapse. 

Post-mortem Appearance. — The changes observed on necropsy are 
those of necrotic degeneration of the cecal mucosa and liver. The walls 
of the ceca are thickened, the mucous membrane ulcerated and covered 
with fibrous membranes and exfoliating necrotic tissue. The liver is 
much enlarged and shows on its surface numerous yellowish areas with 
the centers softened. These areas may be quite small or up to 15 mm. 
(5/8 of an inch) or more in diameter. Other portions of the digestive 
tract are not affected. 

Examination in hanging drop of emulsified tissue of the cecal mucosa 
and the necrotic foci of the liver will reveal the amebae. The organisms 
found in the liver occur as roiuided or oval cells measuring 6-14 microns 
and having a comparatively small nucleus. Smith concluded from his 
investigations that the parasites were not intracellular but lived in the 
tissue spaces. In the liver they are thought to occupy the spaces of the 
necrosed and disappearing liver cells. 



326 PARASITES OF THE DOMESTIC ANIIVIALS 

Control. — The sick animals should be at once separated from those 
which are apparently not infected and the pens and runs subjected to 
thorough cleaning up and disinfection as recommended in other forms 
of poultry parasitism. It is unportant that the .yards be kept dry and 
that the droppings be promptl.y removed and so disposed of that they 
cannot be a source of reinfection. 

Treatment is of little value. As palliative, intestinal antiseptics, as 
eucalyptus or listcrinc, may be tried. 

Amebic Dysentery in Man. — This is a disease occurring in tropical 
and subtropical, and at tunes in temperate regions, the cause of which 
is regarded by pathologists to be an ameba, — Entamba histolytica. Ar- 
tificial production of amebic dysenterj^ has been brought about in dogs 
and cats by rectal introduction of human feces containing the amebse. 
It has been shown in such cases that the parasites invade the glandular 
crypts of the intestinal mucosa from which they penetrate to the sub- 
mucosa and give rise to a hemorrhagic enteritis. In its further course the 
affection is accompanied bj' thickening and destructive ulceration of the 
mucosa. 

The diagnosis of amebic dysentery is by ilemonstration of the ame- 
bae in the stools. They may be differentiated from Entameba coU, an 
intestinal species which is considered to be a harmless commensal, by 
their definite and relatively firm ectoplasm which gives a rigid character 
to the pseudojiodia, enabling the parasites to force their way between 
the epithelium of the crj'pts and into the more deeply Ijnng tissues. The 
nucleus of E. histolytica varies in shape and position with the activities 
of the cytoplasm; it has little chromatin, and no nuclear membrane is 
apparent. The nucleus of E. coli is usuall\- spherical and shows little 
change in position. 

Class II. Flagellata (Mastigophora) 

Protozoa (p. 311). 

As has been stated, there are certain forms among the Rhizopoda in 
which the pseudopodia disappear from time to time to be replaced b}' 
one or more flagella; in other cases there may even be permanent fla- 
gella contributing to the pseudopodia in their function of locomotion and 
prehension. Such flagellate rhizopods are transitional to the Flagellata 
and serve to prevent the drawing of a sharp line of demarcation lietween 
the two groups based upon the possession of flagella. In general it may 
be said of the Flagellata that they are permanently flagellate, the fla- 
gella serving for locomotion and feeding. They exhibit a great diversity 
of form which is to a large extent correlated with the number and loca- 
tion of the flagella. A degree of complexity is exhibited by some free- 
living forms in the possession of a mouth and cj-topharynx, but all par- 



THE PROTOZOAN SUBGROUPS 



327 



asitic forms, and most of those which are free-Hving, obtain their nour- 
ishment by absorbtion through the general surface of the body. 

The parasitic flagellates come within two orders, — Spirochetida and 
Trypanosomatida. 

Order I. Spirochetida 

Flagelkta (p. 326). 

The spirochetes are of somewhat uncertain position because of in- 
complete knowledge of their flagella and life history. They multiply bj^ 
longitudinal division, or it may be bj- transverse division as do bacteria, 
and many writers have placed 
them with the latter organisms. 
They range from one to two 
hundred microns in length, and 
the body is filamentous and 
spiral in form (Fig. 169). Deli- 
cate flagella may be present at 
one or both ends. Nuclei can- 
not be distinctly demonstrated ; 
the nuclear material is prob- 
ably distributed as granules 
throughout the protoplasm as 
in bacteria. Motility is exhib- 
ited by rotatory movements^ 
and the progression may be m 
either direction. 

Excepting in poultiy, the spirochetes are not, so far as known, seriously 
pathogenic in the domestic anunals. The extreme pathogenicity of 
certain spirochetes in man, however, indicates the disease-producing 
possibilities of the group and rates it, potentialh' at least, as a dangerous 
one to all higher animals. 




Fig. 169. — Spirocheta pallida (after Craw- 
ley, from Dofliein, after Schaudinn, Cir. No. 194; 
Bu. An. Ind., U. S. Dept. Agr.). 



Spirochetosis of Fowls 

This disease was first described by Marchoux and Salimbeni who, 
working in Brazil, noted that special varieties were more susceptible 
and suffered more severely from the attack than connnon fowls. The 
condition was originally termed fowl septicemia, or Brazilian septicemia 
of fowls, and is now considered to be due to the presence of the spirochete 
Spirocheta galliiwrum (S. marchouxi) which lives in the blood, is l.^-20 
microns in lennth, and is carried from host to host by the tick Argas 
miniatus. 

The investigators above mentioned distinguish an acute and chronic 
form of the disease, the former characterized by emaciation, drooping, 



3^28 



PARASITES OF THE DOMESTIC ANIMALS 



diarrhea, and anaemia. Toward the end weakness has so far advanced 
that the affected birds are completely helpless and lie with their heads 
upon the ground. Those which survive are said to be immune to fur- 
ther attack. The spiroochete sometimes penetrates the red blood 
cells; it has also been found in the eggs and in the embryonal epithelium 
of the chick. 

It is not known with certainty that the disease exists in this country. 
It is not unlikely, however, that some of the as yet obscure diseases 




Fig. 170. — Hen suffering from acute spirochetosis (after Crawley, from Balfour, Cir. 
No. 1<)4, Bu. An. Ind., U. S. Dept. Agr.). 

of poultry may be found to be due to members of the spirochete group, 
— a sufficient reason for mentioning the Brazilian spirochetosis here. 



Order II. Trypano.somatid.4 

Flagellata (p. 326). 

A number of classifications have been proposed for the.se organisms, 
Salmon and Styles placing them in the order Monadida (Moore, 1906). 
Calkins (1909) classifies them as follows: Subjihylum ]\Ia.stigophora; 
class, Zoomastigophora; subclass, Lissoflagellata ; ordei', Trypanosoma- 
tida; typical genera, Trypanosoma and Trypanoplasma. The same 
author thus describes the order in tabulation: "Organisms of elongate, 
usually pointed form, and of parasitic mode of life; with one or two 
flagella arising from a special "motor" nucleus, and with an undulating 
membrane provided with mj-onemes running from the kinetonucleus 
to the extremity of the cell; one of the flagella is attached to the edge 



THE PROTOZOAN SUBGROUPS 329 

of this membrane throughout its length, and may terminate with the 
membrane or be continued beyond the bodj^ as a free lash." 

All species of the genus Trj^panosoma show a general morphologic 
similarity. In general they may be said to measure from 15-45 microns 
in length, including the fJagellum, and 1-5 microns in thickness. As 
typical of the group, T. theileri, living exclusivelj^ in the blood of cattle, 
may be taken for brief description. The body is spindle-shaped, more 
or less serpentine, and pointed at the ends, from one of which there pro- 
jects a vibratile flagellum. The fiagellum is continued as a marginal 
cord toward the opposite end of the body where it takes origin in a 
minute granule (blepharoplast). In close relation to this granule is a 
deeply staining body which, because of its connection with the motile 
elements of the cell, has been designated the kinetonucleus. Arising 
from the kinetonucleus, the flagellum passes along the body on the 
border of a delicate protoplasmic membrane — the undulating mem- 
bi'ane — toward its free extremity. Centrally located is the tropho- 
nucleus, the nucleus concerned with the vegetative processes of the cell. 
This is clearly defined and usually has the chromatin in the form of 
granules of definite nmnber. The endoplasm is granular and may 
appear vacuolated. Reproduction in the blood of the vertebrate host 
is by longitudinal division following division of the blepharoplast, 
kinetonucleus, and trophonucleus. In some cases the daughter cells 
remain together for a longer or shorter time in a sort of rosette forma- 
tion. 

The members of the genus Trypanoplasma (Cryptobia) have two 
flagella. They are mostly parasitic in fishes; so far as known there are 
no species which attack higher animals. 

Transmission. — The Trypanosoma are parasites of the blood, 
Ijanph, or cerebrospinal fluid of vertebrates, and, with one known ex- 
ception, their transfer is accomplished by the intervention of an inter- 
mediate carrier which is either essential and indirect, or mechanical 
and direct. In the former case a blood-sucking flj^ becomes infected 
by feeding upon the blood of an animal harboring the trypanosomes. 
In the body of the fly the trypanosomes undergo certain changes, 
probably of a revitalizing nature, and for a period of time the flj' remains 
noninfective. When this period has elapsed the trypanosomes within 
the fly resume their ability to infect any host whose Ijlood is reached by 
the piercing mouth parts of the fly. Furthermore, such flies remain 
infective for an indefinite period, probably for the remainder of their 
lives. 

By the direct or mechanical method of transfer the flj', after having 
bitten an infected animal, very shortly afterward visits a healthy one 
and may inoculate it directly with its contaminated pi-oboscis. If the 
fly draws the blood of a sick animal and then successively visits two 



330 PARASITES OF THE DOMESTIC ANIMALS 

healthy ones, the second of the latter will not usually contract the 
disease. This is due to the fact that the proboscis of the fly, charged 
with the trypanosonies from the blood of the sick animal, becomes 
cleaned of the organisms in biting the first of the healthy ones. Anj^ 
biting arthropod may transmit by the direct method; the ability to 
infect is usually limitetl to a few hours from the time of biting an in- 
fected animal, though imder experimental observation it has been re- 
tained for a consideiably longer time (see Glossina, p. 44). 

Nagaxa 

The fundamental work ujion this disease was carried on in Zululand 
b\- Bruce who, in 189.5, discovered that nagana, or the so-called tsetse 
fl\' disease, was caused bj- a trypanosome which, after its discoverer, 
has been named Trypanosoma brucei. 

"Nagana, or fly disease," Bruce writes, "is a specific disease which 
occurs in the horse, mule, donkej', ox, dog, cat, and many other animals, 
and varies in duration from a few days or weeks to many months. It 
is invariably fatal in the horse, donkey, and dog, but a small percentage 
of cattle recover. It is characterized by fever, infiltration of coagulable 
lymph into the sul)cutaneous tissue of the neck, abdomen, or extrem- 
ities, giving rise to swelling in these regions, by a more or less rapid 
destruction of the red blood corpuscles, extreme emaciation, often 
blindness, and the constant occurrence in the blood of an infusorial 
parasite." 

Nagana is a Zulu word which, according to Bruce, refers to the state 
of depression and weakness chai-acteristic of the disease. 

Nagana exists, iiarticularl^- in low and humid regions, throughout 
Africa with the exception of Tunis, Algeria, and Morocco, and most of 
the country- south of the Tropic of Capricorn. The disease is supposed 
to he transmitted mainly the by the tsetse Hy Glossina 7norsitans, though 
other species [jrobably play an equal part in this respect. Etiologic 
reference to nagana has already' been made in the review of the work of 
Bruce under the subject of Glossina (p. 44) and need not be repeated 
here. 

Plate V. — Various Species of Trypanosoma. I. Trypanosoma lewisi, of the rat. 
2. Trypanosoma lewisi, multiplication rosette. 3. Trypanosoma lewisi, small form re- 
sulting from the disintegration of a rosette. 4. Trypanosoma brucei, of nagana. 5. 
Trypanosoma equinum, of caderas. 6. Trypanosoma gambiense, of sleeping sickness. 
7. Trypanosoma gambiense, undergoing division. 8. Trypanosoma theileri, a harmless 
trypanosome of cattle. 9. Trypanosoma transvaliense, a variation of T. theileri. 10. 
Trypanosoma avium, a bird tr\'panosome. 11. Trj-panosoma damoniae. of a tortoise. 
12. Trypanosoma soleae. of the flat fish. 13. Trypanosoma granulosum. of the eel. 14. 
Trypanosoma rajse, of the skate. 15. Trypanosoma rotatorium, of frogs. 16. Cryptobia 
borreli, of the red-e.ve (a fish). (After Crawlej', from Laveran and Mesnil; Cir. No. 194, 
Bu. .\n. Ind.. V. S. Dept, .^gr.) 



332 PARASITES OF THE DOMESTIC ANIMALS 

Surra 

This name has been given to a disease of horses, camels, and dogs of 
Asia caused by Trypanosoma evansi, which in 1880 was found by Evans 
in the blood of affected horses. Surra occurs in Southern Asia, the 
East Indies, the Philippines, Korea, Australia, and among the drome- 
daries in Northern Africa where it is known under the name of mbori. 

Symptoms. — In its constant and progressive anaemia and cachexia 
the disease closeh^ resembles nagana. At its outset there is a rise of tem- 
perature which in some cases may be followed by an urticarial eruption. 
Edema appears under the skin of the belly and limbs, and the eyelids 
become puffy with conjunctiva congested. The appetite is usually re- 
tained, but in spite of this there is loss of flesh and strength. Later the 
appetite is lost, there is great weakness, and the wasted and enfeebled 
animal may fall and be unable to again get upon its feet. 

Course. — Horses invariably die in from one to several months after 
the onset of the disease, though in some cases death may occur suddenly 
in the early stages. In camels the disease runs a much longer course. 
Cattle, though they may harbor the parasites in their blood, generally 
resist the disease. 

Infection. — A specific carrier of the organism causing surra is not 
known. Tsetse flies are not found in Asia, but it has been determined 
that the stable fly {Stomoxijs calcilrans) and the horsefly {Tabanus stri- 
atus) of Asiatic countries can transmit the disease by their bite. It is 
believed by some that the horsefly is the principal carrier. So far as 
known the flies carry the disease from animal to animal directly by means 
of contaminated mouth parts, and are unable to infect for more than 
one or two days after having drawn the blood of an infected animal. 

Mal De Caderas 

Mai de caderas (disease of the hip) is a trypanosomiasis occurring in 
horses throughout the greater part of South America, caused by Try- 
panosoma equinum, which was discovered by Ebnassian in the blood of 
horses in Argentina in 1901. The occurrence of the disease by natural 
infection is almost exclusively among horses and mules, the former of 
which are the more susceptible. A number of other mammals may be 
successfully inoculated, among them the hog, rabbit, guinea pig, rat, and 
mouse. 

Symptoms. — P'ollowing a statement that, owing to its great ravages 
in certain parts of South America, cattle have to be used for riding purpo- 
ses, Laveran and Mesnil (Trj'panosomes and Trypanosomiases, Eng- 
lish edition) describe the symptons of the disease as follows: 

"The first sign of the disease in horses is wasting, which rapidly pro- 



THE PROTOZOAN SUBGROUPS 333 

gresses in spite of a good appetite. Tlie temperature is often raised to 
104° to 105.8° F. After a varible time it is noticed that the hind quar- 
ters are weak, and that the animal drags its legs, the hoofs grazing the 
ground. These symptons increase and become characteristic, so that 
when the animal is made t ) walk it staggers along, the hind quarters 
swaying from side to side. On account of this sjanpton the name mal 
de caderas, or disease of the hind quarters, has been given to the disease. 
There comes a tune when the animal is unable to stand ; if in the stable, 
it leans up against a wall or seeks other support: if in the open, it stag- 
gers and falls. After thus falling to the ground an animal maj' still live 
for several days if it be fed; otherwise the inevitably fatal end is 
hastened by inanition." 

Infection. — The mode of natural infection is not as yet known. The 
observed fact that horses separated from affected anunals only by a 
fence remain healthy in spite of the presence of piercing flies, would indi- 
cate that these insects are not the transmitters. Until something definite 
is established as to the transmitting agent, no certain preventive meas- 
ures can be adopted. 

DOURINE 

Dourine is an infectious disease of the horse and ass affecting prima- 
rily the genital tract. It is due to Trypanosoma equiperdum, transmitted 
from animal to animal in the act of copulation. The disease is vari- 
ously named "maladie du coit," " el dourine," or " dourine," according 
to the country in which it is found, dourine, which is from the Arabic for 
"unclean," being the term most commonly employed for it in the United 
States. It is supposed to have been introduced into Continental Eu- 
rope early in the nineteenth century by horses imported for breeding, 
especially those from the Orient where the disease has long existed. 

In the United States dourine first appeared in Illinois where it was 
recognized by Dr. W. L. Wilhams in 1886. The source of the infection 
was found to be imported Percheron stallion, and it had been dissemi- 
nated for some time before the ti'ue nature of the malady became known. 
By the application of rigid preventive measures, the disease was eradi- 
cated from Illinois in 1888, but it had been carried by a stallion to Ne- 
braska, where an investigation of an outbreak in 1892 b.y an inspector of 
the Bureau of Animal Industry revealed that upward of two hundred 
mares and stallions in the northwestern part of that state were affected 
with the disease. Measures taken by the federal authorities brought this 
outbreak under control for a time, but a few j-ears later the infection 
again appeared in the same part of the state. In 1901 there was an out- 
break in the Pine Ridge and Rosebud Indian Reservations of South 
Dakota, and in 1903 the disease was reported in Van Buren County, 
Iowa. It was again found in Tavlor Countv, Iowa, in 1911. Thus dour- 



334 P-\RASITES OF THE DOMESTIC ANIMALS 

ine has appeared at various times within certain Kmits in the United 
States. 

Infection. — Dourine is a peculiar trypanosomiasis in that there is 
no intermediate carrier of the trypanosome specifically responsible for 
it. Like the spirochete of human syphilis, it is inoculable by contact, the 
infection usually occurring during the act of copulation, though reported 
cases of the disease in geldings and in mares which have never had the 
stallion would indicate that its transmission is not entirely by copulation. 
It may be artificially transmitted to horses and to other susceptible 
animals, as dogs and rabbits, by inoculation with blood from animals 
affected. Sexual intercourse is, however, by far the most common means 
of natural infection, the trypanosome reaching the blood by penetrat- 
ing the intact mucosa of the genital tract. 

Symptoms. — The symptoms of dourine as given by John R. Mohler 
(Bureau of Animal Industry, Bulletin No. 142, 1911) are, with some 
omissions, here quoted. 

"There are many variations in the symptoms of dourine, and this is 
jjarticularly true of the disease as it occiu's in this country. Two dis- 
tinct stages may be noted which vary somewhat from those described 
in textbooks, but probably no more than could be expected when 
differences of climatic conditions and methods of handling are taken 
into con.sideration. 

"The first stage chiefly concerns the sexual organs, and therefore 
differs somewhat in the male and female. In the second stage symptoms 
indicating an affection of the nervous system are more prominent and 
are not (leiK>ndent on the sex of the animal. 

"Following a variable period of incubation of from eight days to two 
months, there is seen in the stallion an irritation and swelling about 
the penis first noticed in the glans. This swelling extends throughout 
the organ, and the penis may be continually protruded and fi'equent 
erections noticed. The edematous swelling also involves the groin, 
with enlargement of the adjacent inguinal glands, and extends forward 
along the abdomen. In a few days small vesicles or blisters appear on 
the penis, which break, discharging a yellowish serous fluid and leaving 
irregular raw ulcers. Where ijrimary ulcers are in proximity to each 
other there is a marked disj^osition to coalesce, a large raw surface with 
irregular border resulting. The ulcerative process may form a wound 
extending almost entirely around the penis. The ulcers show a tendency 
to heal rapidly, leaving white cicatrices which are permanent. In some 
cases the urinary meatus is very red and swollen, and according to some 
observers, especially European, more or less thick catarrhal exudate 
is discharged from its oriface. This condition, however, has been rarely 
seen in cases in this country, a more or less continuous dri])]jing from 
the urethra of a j-ellowish serous-like discharge alone being present. 



THE PROTOZOAN SUBGROUPS 335 

The stallion retains his full genetic instinct and becomes very amorous 
when brought in the vicinity of mares. If allowed access to mares in 
season, service is often impossible, clue to the fact that a complete 
erection of the penis does not occur. The testicles may be involved and 
tender to pressure, and abscess formation may occur with sloughing. 

" In the mare the first S3anptoms may be so slight as not to be noticed 
bj^ the owner. The disease being the result of copulation, begins with 
swelling and inflammation of the vulva and vagina. The labia are 
continually everted, exposing the clitoris, which is constantly in a state 
of erection. There will also be a muco-purulent discharge like that 
coming from the penis of the male, which may be shght or profuse in 
quantity. The mare will switch the tail, appear uneasy, and urinate 
frequently. Shortlj^ papules and vesicles appear on the external vulva, 
as well as on the mucosa of the vulva and vagina. These vesicles soon 
rupture, but before doing so the contents undergo a change from a 
transparent to a purulent fluid. The rupture of these pustules is the 
initial stage in the formation of deep, angiy. ulcers. These ulcers show 
a tendency to heal rapidty, but invariably leave a cicatrix. On the dai'k 
skin of the external vulva the scars will always be white. This de- 
pigmentation is permanent. 

"Sometimes, especially in the mare, the above-described lesions tend 
to disappear gradual!}^, and in case the mare is not served again the 
disease may remain in abeyance for months or a year. The apparent 
recovery, however, is not permanent, and any excessive work or excite- 
ment may set up the disease anew. In case an affected mare conceives, 
she is liable to abort at any time during her term of pregnancJ^ When 
the fetus is carried to full term, it occasionally is a weak or miperfectly 
developed foal, but in this country many fine colts have been born to 
affected mares. 

"The nerVous or constitutional disturbances of the second stage may 
not come on for months or even a year after the appearance of the local 
lesions, and are similar in both male and female. They consist of a 
general nervous disorder with staggering, swaying gait, especiall}' in 
the hind limbs. The annual becomes extremely emaciated, particularly 
in the hind ciuarters, and the abdomen assumes a "tucked-up" appear- 
ance. The first indication of paralysis will be noted in traveling, when 
the animal fails to pick up one of the hind feet as freely as the other. 
There is a tendency to drag the foot partially. This condition maj'' 
shift from one hind foot to the other, or both may become affected 
simultaneously. Twitching of the superficial muscles has been noticed 
in several instances. Urticarial eruptions or plaques may break out 
over various parts of the bodj-, and there may be noticed pruritus of 
the skin, which causes the animal to rub itself frequently. The teni- 
peratiu'e of the animal seldom goes above 101° or 102° F. AVhcn the 



336 PARASITES OF THE DOMESTIC ANIMALS 

paralysis of the hind limbs starts to appear, it usually progresses rapidly, 
the horse goes down, is unable to rise, and dies in a short time from 
nervous exhaustion." 

Control. — As dourine is transmitted and spread only bj* copulation, 
its eradication is a less difficult problem than in trypanosomiases which 
may be carried li>- flies. So little benefit is to be derived from medicinal 
treatment that in this country, where the disease has appeared only 
in restricted areas, it is not advisable. While cure may be possible, 
an apparently cured animal maj' carry the trj'panosomes for months 
in the sexual organs, and relapses are likely to occur. In areas where 
the disease appears measures of eradication must be based upon the 
prevention of infected animals from lireeding. 

To confine the losses to the minimum, therefore, the prompt castration 
of affected stallions and the destruction of diseased mares is essential. 
Spaying of such mares is not a sufficient precaution from the fact that 
they may be sold and an attempt made to breed them, thus infecting 
the stallion and through this source spreading the disease. Restrictions 
in the movement of horses in infected districts and frequent reinspection 
are further state and federal measures for confining an outbreak so far 
as possible to its original limits. 

Trypanosoma americanum. — This trypanosome is found in cultures 
of blood from healthy- American cattle. It deserves mention here on 
account of its common occurrence, though it appears to be harmless. 
A report by Crawley upon his extended study of this organism will be 
found in Bureau of Animal Industry Bulletin No. 145 (1912). 

Class III. Sporozoa 

Protozoa (p. 311). — The Sporozoa are all parasitic. Though without 
motile organs, thej' are capable of moving from place to place, in some 
cases b_y means of pseudopodia. Reproduction is mainly by spore 
formation, either asexual or sexual. There are a number of forms, 
however, in which sunple reproduction occurs, and the group comprises 
organisms with life histories as yet not fully known. The Sporozoa, 
therefore, is a division to be regarded as provisional, containing at pres- 
ent organisms which when their life histories are fully made out maj' 
be more accurately placed with other divisions of the Protozoa. 

Based upon the belief that the Sporozoa are polyphyletic; that is that 
all have not the same ancestral history, they have been placed in two 
divisions, — Telosporidia and Neosporidia, the former regarded as ' 
descended from the flagellates, the latter from the rhizopods. Of the 
Telosporidia but two orders are to be considered here, — Coccidia and 
Hemosporidia. The Neosporidia has one order, — Sarcosporidia, con- 
tainuig parasites of domestic animals. 



THE PROTOZOAN SUBGROUPS 337 

Order I. Coccidia 

Sporozoa (p. 336). — The Coccidia are cytozoic or cell-infesting para- 
sites, attacking epithelium of invertebrate and vertebrate animals. Re- 
production is bj'" schizogony and by sporogony, the asexual and sexual 
generations alternating in the life cycle. In species parasitic to domestic 
animals the fertilized cell produces sporoblasts covered bj^ a sporo- 
cyst membrane. 

Life History. — The life cycle is similar to that of the malaria organ- 
isms except that no arthropod intermediate host is required for the 
sexual reproduction. Infection with Coccidia is with the encysted stage 
(oocyst) by way of the mouth. Hence the parasites are almost exclu- 
sively found in the epithelium of the almientr_y canal and organs con- 
nected with it. Reaching the stomach and duodenum, the oocyst is 
acted upon by the digestive juices and the sporozoites contained in the 
cyst are liberated. These enter the epithelial cells of the mucosa. Within 
the cells they lose their spindle form and enter the stage of the tro- 
phozoite in which they grow to a size depending somewhat upon that 
of the invaded cell. By the process of schizogony the trophozoite di- 
vides into a number of small protoplasmic masses which are the mero- 
zoites or asexuallj^ formed spores. These invade other cells and in the 
same manner grow into another generation of merozoites. By many 
repetitions of this cycle a large number of cells are invaded and de- 
stroyed, arid the death of the host animal may follow as a result. After 
a number of asexual cj-cles some of the merozoites do not grow and di- 
vide into another generation of merozoites, but develop into stages which 
begin the sporogonous or sexual cycle. In this process the female tro- 
phozoite instead of dividing develops into an egg or macrogamete. The 
male trophozoite, by division, forms minute male reproductive elements 
or microgametes. By their motility the microgametes reach and fer- 
tilize the macrogametes which, laecoming suri'ounded by a resistant 
membrane, arrive at the stage of the ooc>-st. Within the oocyst a nmn- 
ber of spores may be formed, each inclosed in a protecting membrane 
and constituting a sporoc\'st. By division each sporocyst forms two 
or more sporozoites, and thus the sexual cycle is completed. Where the 
parasites are in the epithelium of the alimentary' tract or its commu- 
nicating organs, the oocj'sts pass to the exterior with the feces. In other 
cases it may be that they can only reach the outside after the death and 
disintegration of the host. 

The effect of coccidiosis upon the animal is l)rought about by the ex- 
tensive destruction of cells resulting from the repeated production of 
merozoites by schizogny. This j^rogressive reproduction and cell de- 
struction would in every case result in the ileath of the animal were it 
not that the number of schizogonous generations is limited. The cell 




Plate VI, Fig. 1. 



1 


( 


^^^^^^^^^^^^^^^^^^H 


M 


'1' 






^ ^JI"**^i^^^^H 





Plate VI, Fig. 2. 



Plate. VI. — Fig. 1. — Percheron stallion, showing condition at the time of purchase. 
Fig. 2. Same stallion after doui-ine had developed. Spots on side and croup give location 
of plaques. (After Mohler, Bui. No. 142, Bu. An. Ind., U. S. Dep Agr.). 




Plate Vn, Fu;. 1. 



/ 


mi 


■o 





Plate VII, Fig. 2. 



Plate VII. — Fig. 1. — Percheron mare, showing chronic dourine. Observe the "tucked 
up" abdomen and emaciation, the mare having lost over 700 pounds in the previous four 
months. Fig. 2. — A mare in the last stage of dourine. Notice the position of the oil hind 
foot and the straightened hock joints. (After Mohler, Bui. No. 142, Bu. An. Ind., U. S. 
Dept. Agr.). 



342 PARASITES OF THE DOMESTIC ANIMALS 

destruction ceases with the beginning of the sporogonoiis cycle, and, if 
the acute stage of the disease is survived, the animal tends to recover, 
the destroj'ed cells being replaced more or less completely by newlj^ 
formed ones. Thus it may be said that the disease is self-limiting. 
Eimeria stiedae. — Coccidia (p. 337). — This coccidian, also known 
as Coccidium ovijorme and C. cuniculi, is the species commonly found 
in the liver of domestic rabbits. Most frequentl.y it attacks the epithe- 
lium of the Ijile ducts where it causes destruction of cells and pathologic 
changes in the liver by which the secretion of bile is reduced. The con- 
dition affects rabbits seriously and deaths occur as a result of it. 

Eimeria diedce is considered by some authors as a cause of coccidiosis 
in man. 

Diplospora bigemina (Isospora bigemina). Coccidia (p. 337). — In 
a report upon their work with this coccidian Hall and ^^'igdor (Journal 
of the American Veterinary INIedical Association, April, 1918) state that 
in two hundred dogs examined at Detroit, Micliigan, it was found in 
fifteen, or slightly over seven per cent. From this finding they suggest 
that the parasite may be more common in American dogs than our pres- 
ent lack of information would indicate. 

In reference to the pathogenesis of Diplospora higemina, these au- 
thors may be further quoted from the same article as follows: 

"As regards the pathological significance of D. bigemina, we have 
but little information, but the following notes may serve some purpose: 
Dog No. 130 presented a clinical picture of distemper and died of pneu- 
monia, probabl>' due in part to distemper and partly to an accident 
in drenching. The small intestine showed diffuse hemorrhagic points, 
most pronounced in the ileum, especially' the lower ileum near the valve. 
Scrapings of the mucosa showed the coccidia to be most abundant in the 
ileum, less so in the jejunum and least so in the duodenum. These 
findings of increasing numbers of coccidia with increasing severity 
of lesions may be correlated, but in the absence of sections indicating 
the relation of the coccidia to the hemorrhage, we do not care to hazard 
a definite opinion. Dog No. 173 showed numerous fine petechiae in the 
intestinal nmcosa, and these were especally numerous in the Peyer's 
patches, giving these a uniformly dark appearance. No sections were 
made and this dog had shown no oocysts in the feces for fort.v-five daj-s. 
Dog No. 127 showed innumerable pinpoint petechia in the ileum, but 
it would be unsafe to draw conclusions based on this one dog, as the 
animal figured in other experiments. The intestine of dog No. 223 was 
macroscopicallj' normal except for the presence of hook-worm petechiae. 
In view of the fact that coccidia are destructive to epithelial tissue and 
that some species fairly closelj- related to D. higemina are known to be 
highly pathological, it would seem reasonable to suppose that D. hig- 
emina might he distinctly ])athological at times, though the apparent 



THE PROTOZOAN SUBGROUPS 343 

good health and lack of post-mortem lesions in other dogs makes it cei'- 
tain that it often does no visible damage." 

Coccidium zurni. Coccidia (p. 337). — Red dysentery of cattle is 
attributed to this coccidian. The disease occurs in Europe, generally' 
among j^oung animals as' an enzootic. The attack of the parasites upon 
the cells of the intestinal mucosa causes extensive hemorrhage, the red 
diarrhea resulting from the mixture of the blood with the feces. Mild 
cases, particularly^ in adult animals, may soon recover. Severe cases, 
occurring particularly in young animals, may run a hyperacute course 
and terminate fatallj' within two days, or an acute course of five to ten 
days may precede this termination. 

In the report of the Committee on Medicine and Surgery submitted 
at the meeting of the Pennsylvania State Veterinary Medical Associa- 
tion, held in January, 1918, Dr. W. J. Lentz, of the University of Penn- 
sylvania, called attention to cases of intestinal coccidiosis of cattle 
which had come under his observation in the State of Delaware. His 
report as published in the Journal of the American Veterinary Medical 
Association for November, 1918, follows: 

"Was asked to consult with a veterinarian on an interestmg condition 
in a herd of grade Holsteins. Owner had lost four or five heifers over a 
period of about two weeks, ranging in age from six months to eighteen 
months. All presented similar symptoms. There was first noticed a 
serous, fetid, black diarrhea. Fever was rareh' in evidence at any time. 
The diarrhea after a few days changed to mucus, with the passage of 
blood clots with the mucus and feces from time to time. Straining was 
very marked. Appetite somewhat impaired but, nevertheless, partook 
of sonre food, but finall.v, in about six to eight days, became very dull, 
refused food, emaciated rapidly, rectum became i-elaxed, temperature 
subnormal, pulse hardly perceptible, and these sjmaptoms of collapse 
were sodn followed by death. On arrival at the farm found six to eight 
calves and one adult cow presenting some of the sjinptoms mentioned, 
and, inasmuch as one was about to die, it was destroyed and posted. 
Lesions were confined to the large intestine. No apparent pathological 
change in any other organ. The mucous membrane of the large in- 
testine, which was almost emptj-, was red brown in color, soft and 
spongy, and everywhere coated with a bloodj- mucus. The back of the 
knife, after the intestine was slit open, was jjassed over the mucous 
surface and the bloodj' mucus scraped off', when it was noticed that 
large superficial ulcers, white in color, and about the size of one's palm, 
were present throughout the whole extent of the large intestine from 
the ceciun to the anus. Some of the mucous patches were scraped oft" 
and collected in a bottle, also some of the blood and feces. On micro- 
scopic examination, coccidia were detected. A diagnosis of "intestinal 
coccidiosis," or "red dysentery," was therefore made. Treatment 



I 2 



20 2( 






® 



\ jg 







#/^; 



ri,\TK VIII, Flc;. 1, 




19 I 



2 i^.-V 



/^, 



■■^ > ^ 






. '- -<D«»*^ ■7'" 
9i_- ^ V 



3 , 



nm»jf 



lOS ' /i 




i'W' , A ,i 



-''1^ 






Plate VIII, Fig. 2. 



THE PROTOZOAN SUBGROUPS 345 

Plate VIII. — Coccidian Life Cycle. — Fig. 1. 1. Sporozoite released in intestine of 
host. 2. Penetration of sporozoite into epithelial cell. 3, 4. Growth of sporozoite into 
trophozoite. 5, 6, 7. Schizogonous cycle. Nuclear division, followed by division of 
entire trophozoite into a large number of merozoites. 8. Free merozoites, which for an 
indeterminate number of generations merely repeat the schizogonous cycle, behaving 
precisely as do the sporozoites. Eventually, however, the sporogonous cycle is initiated, 
which proceeds as follows: 9a. Undifferentiated female cell. 9b. Undifferentiated male 
cell. 10a. Differentiated female cell. 10b. Differentiated male cell. 11, 12. Formation 
of the mierogametes, one male cell producing many microgametes. 13a. Macrogamete. 
One female cell produces but one macrogamete. 13b. Ripe microgamete. 14. FertiKza- 
tiou. 15, 16, 17. The zygote. 18. Beginning of spore formation. 19. Completion of 
spore formation. 20. Formation of the sporozoites within the spores. 21. Release of the 
sporozoites in the intestine of the host. Fig. 2. — Introduced for comparison with the 
more typical cycle shown in Fig. 1. Here the parasite penetrates and comes to rest in the 
nucleus instead of the cytoplasm, and there is sexual differentiation in the schizogonous 
cycle as well as in sporogony. (After Crawley, from Mense's "Handbuch," after 
Schaudinn, Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 

suggested: Pearson's creolin well diluted with milk or water, also large 
doses of camphorated tincture of opium, and rectal injections, using 
garden hose and funnel, of a two per cent, creolin solution, alternating 
night and morning with a one per cent, alum solution. A week later 
received word that all were doing nicely and no deaths." 

In Europe outbreaks of red dysentery similar to that of cattle have 
occurred in sheep. 

CocciDiAL Enteritis of Chicks 

The use of the name "white diarrhea" for this coccidiosis tends to its 
confusion with bacillary white diarrhea, which is a fatal septicemia of 
chicks caused by Bacterium -pullorum. Coccidial enteritis or coccidiosis 
of chicks is caused hy Eiraeria aviimi {Coccidium tenellum), which attacks 
the epithelium of the intestinal mucosa, usually that of the ceca. Occa- 
tionally the infection is found in other organs. The disease is usually 
seen in chicks from two to ten weeks old. 

Symptoms. — The symptoms are merely suggestive of coccidiosis as 
they do not materially differ from those of some other diseases of poul- 
try. The affected chicks droop and are inclined to stand about by them- 
selves with eyes closed and feathers ruffled. In most all cases there is a 
diarrhea with whitish-colored discharge which stams and mats the 
feathers below the vent; a bloodj' diarrhea gives evidence of coccidial 
infection. If the discharge is examined under the microscope large 
mmibers of circular or slightly oval oocysts may be found. Death usually 
occurs after a course of three to four days. 

Post-morten Appearance. — Post-mortem examination reveals the 
ceca much enlarged. Their contents maj^ be normal or they may be 
packed with a yellowish white or bloody semiUquid material. The 
conclusion that the chicks are not infected with coccidia should not be 
made from the absence of enlarged ceca, as occasionally there is no 



34.6 PARASITES OF THE DOMESTIC ANIMALS 

enlargement of these organs nor abnormal appearance of their contents. 
Not infrequently the enteritis involves the entire length of the intestines. 
For a positive diagnosis microscopical examination of the intestinal 
contents or of the sectioned intestinal wall is necessary. Spreads of 
scrapings from the cecal mucosa examined under the microscope will 
reveal epithelial cells much distended liy the development of the par- 
asites within them. It is as a result of this invasion that the cells finally 
break down antl separate from the underlying stroma to become a part 
of the pasty catarrhal exudate which characterizes the fecal discharge. 

Infection. — Though the fatalities are usually among the j'oung 
chicks, the coccidian which causes the disease may be found in chickens 
of all ages and it may be spread from this source. Infection is by food 
and ingested .soil or water contaminated by droppings which contain 
the cysts. It has been demonsti'ated that the cysts may remain infective 
for a year or more, therefore chickens may become infected if allowed 
access to yards where those harboring the pai'asites were kept the year 
previous. 

Control. — There are no drugs which have been found to he of value 
in treating the disease, therefore control is the essential consideration in 
contending with it. Morse states (Bureau of Animal Industry Cir- 
cular No. 128, 1908) that this must begin with the eggs used for hatching. 
"These," he writes, "should be thoroughly and antiseptically cleaned 
by wiping in ninetj'-five per cent, alcohol. If artificial incubation is 
used (and in this method lies the great hope of success), the incubator, 
if used liefore, should, previous to receiN'ing the eggs, be carefully washed 
with antiseptic solutions and exposed to the sun. The egg tray should 
be scalded or flamed. The floor of the nursery should be movable, so 
that it may be taken out and sterilized, and if made of burlap the old 
piece should Ije torn off and a new piece mounted on the sterilized frame. 
The same precautions should l)e used with the Ijrooders. The soil to 
which the chicks have access should be well covered with lime, dug up, 
and exposed to the dr\'ing effects of the sun and air. If natural in- 
cubation is practiced the hen for a week or two before being set should 
be ti'eated with one-quarter to one-half grain doses of sulphate of iron 
dailj% with occasionally an active purgative, such as calomel, one grain, 
or castor oil, one-half teaspoonful containing five to ten drops of tur- 
pentine. The eggs, cleansed as directed above, should be placed in a 
perfectly fresh nest, which may be sprinkled from time to time with a 
little lime. After hatching, the hen with her chicks should be placed- 
upon ground that has been thoroughly sterilized, as described above, 
and at least every few days moved to fresh ground which has been 
treated in the same way and from which all chickens have been de- 
barred." 

Fiu'ther preventive measures are the removal of visibly sick chicks 



THE PROTOZOAN SUBGROUPS 347 

from the flock, either keeping them isolated or kilUng and burning them. 
It is better to put all of the chickens on new ground if possible, other- 
wise the ground should be covered with lime and spaded so that it may 
be exposed to the drying effect of the sun and air. All litter and nesting 
should be burned and a thorough cleaning up of the quarters followed 
by the application of a strong disinfectant solution. After drjdng, 
the floors may be protected from recontamination somewhat by covering 
them with shavings, chopped bedding, or other absorbant material, 
which is to be cleaned up and burned daily. Boards should be placed 
beneath the roosts to receive the droppings for convenient daily removal. 
Contamination of feeding and drinking vessels can in a measure be pre- 
vented by elevating them somewhat from the ground. They should at 
all times be kept clean; daily treatment with scalding water or flaming 
followed by exposure to the sun will do much to eliminate the source 
of the infection. 

Order II. Hemosporidia 

Sporozoa (p. 336). — The Hemosporidia are Sporozoa which dwell in 
the blood where they invade the corpuscles, hence are cj^t-ozoic. Flag- 
ellated stages appear in their life history, and many protozoologists 
suspect that the entire group has been evolved from the flagellated 
Protozoa. Comparing the life historj^ of the malaria organisms (p. 318) 
with that of .the Coccidia (p. 337) a distinct difference will be noted in 
the method of infection, the hemosporidian, as is true of others of the 
group, being transmitted from the blood of one anunal to that of an- 
other by means of a known intermediate host, while the Coccidia infect 
directly, usually by food or water bearing the cysts. In diseases caused. 
by Hemosporidia, the infection, due to the activities of the intermediate 
host, is morQ widely disseminated, and large numbers of animals may 
be seriously and fatally attacked. As blood parasites, therefore, the 
Hemosporidia may be rated with the trypanosomes in pathologic im- 
portance. 

Texas Fever 

Tick fever, Splenic fever. 

Smith and Kilbourne in 1893 found small parasites in the red blood 
corpuscles of cattle suffering with Texas fever. Due to their frequent 
occuri'ence in pairs, the^v were given the specific name hicieminum, and the 
genus was nained Pijrosoma. The later generic name Piroplasma was 
derived from their often assuming a pear-like fornn, and the name now 
generally used for the hemosporidian causing Texas fever is Piroplasma 
bujeininum (Fig. 171). 

The nredium by which the organism is transmitted is the cattle tick 
Margaropim aiinidatus, which crawls upon its host as a larva, attaches. 




348 PARASITES OF THE DOMESTIC ANIMALS 

and here undergoes its complete development. (Ref. Margaropus annul- 
aitis, Life History, p. 148.) For a number of days following her fer- 
tilization the female tick engorges with the blood of her host and then 
drops to the ground where a few days later she deposits her eggs and, 
having completed her cycle, soon dies. The parasites contained in the 
blood upon which the tick has fed reach the eggs and 
arc present in the larval ticks when these are hatched. 
Thus the larvie have the power to infect any susceptible 
animal to which they attach. 

In the first stage of development after gaining the 
circulation the piroplasma is within the red corpuscle 
as a single body near the corpuscle's margin. Later it 
Piro^lasnV'^i ^'ivides into two bodies which remain slightly connected 
eminum (after by a Small filament. A single corpuscle may contain as 
Crawley, from niany as four or even six parasites. The doubled bodies 

DofJein, Cir. No. . " • • ji u j i i x 

194. Bu. .\n. ind. PnJ^rge, assunung a spmdle-shaped and later a pear- 
U. s. Di-pt. Agr.) shaped appearance. Finally, as a result of this invasion, 
the corpuscles break down, and the parasites become 
free bodies in the plasma. That a multiplicative stage occurs within 
the bovine host is evidenced from the fact that inoculation of sus- 
ceptible cattle with a small ciuantity of \'irulent blood will produce the 
disease with the development of myriads of the parasites in the blood of 
the inoculated animals. 

Occurrence. — Numerous attempts have been made to produce Texas 
fever in other species of animals by inoculating them with infected blood 
from cattle. That all of these exiieriments have proved negative in- 
dicates that the disease is one purely bovine. All bovine animals that 
have never been exposed are susceptible, and in all cases natural in- 
fection with the protozoan causing the disease is due to puncture by 
the cattle tick. 

The disease exists in European and Asiatic countries, Africa, Austraha, 
and the Philippine Islands. It was probably introduced into the United 
States by cattle brought over by the early Spanish settlers. The terms 
" Texas fever " and " southern cattle fever " are misleading to some in 
gi\ing the impression that the disease is confined to the Southern States. 
Southern cattle carrj'ing the infecting organism in their blood, though 
themselves possessing degrees of immunity to Texas fever, disseminate 
it through ticks from their bodies among cattle in the North or among 
those of the South which are susceptible to the disease in a virulent 
form. 

Exposure and Development. — The period from exposure to tick in- 
fested pastures or pens to the appearance of the disease depends upon 
the time which elapses from the dropping of the female ticks from the 
southern cattle to the hatching of the larvae from their eggs, and this 



THE PROTOZOAN SUBGROUPS 349 

will be influenced bj^ climatic conditions. If the larval ticks are already 
present and at once attach to the exposed animals symptoms of the fever 
may develop ten to twelve daj^s later. Where the susceptible animals 
are placed upon pastures, in peias, or other places immediateh^ after 
these have been infected with ticks from southern cattle, a period must 
intervene covering egg-laying and hatching of the larvse before the 
northern anmrals become inoculated. In summer this period iaa,y oc- 
cupy from twenty to forty days; m cooler weather it takes longer for the 
eggs to hatch, and under such conditions sixtj^ days or longer may be 
required before the infective generation of ticks appears. Thus, de- 
pending upon season and temperature, the disease may appear in twelve 
days to two or three months after exposure (see life history of Texas 
fever tick, page 148). 

Symptoms. — Two distinct types of Texas fever are presented, — an 
acute fatal and a chronic form, from the latter of which the animals 
usuall}' recover. Whether the fatal or the milder tj^pe appears will de- 
pend upon season and the susceptibilty of the animals. When northern 
cattle and those raised in tick-free districts in the South are attacked in 
the hot weather of summer, the acute form occurs. If the susceptible 
animals are affected in the latter part of autmiin the milder chronic sjiii- 
ptoms appear, and it is by this type of the disease that partly immune 
southern cattle are affected at any season, the fatal form rarely attack- 
ing these aniinals. 

The Acute Type. — In this form of the disease the onset of the sj^mp- 
toms is rapid. The animal is depressed and stands or Hes down apart 
from the herd, there is loss of appetite and rumination ceases. The tem- 
perature rises within twenty-four to forty-eight hours to 107° or 108° F., 
the fever accompanied by increase in the rate of pulse and respiration. 
During the ^arly stages of the disease there is constipation which 
is generally followed bj^ diarrhea. The hemoglobin released by the 
disintegration of the corpuscles causes a blood-stained uriae (hemoglobi- 
nurea), from which symptom is derived the name "red water," some- 
times given to the disease. Cerebral disturbances, exhibited by stag- 
gering, disorders of vision, or delirium, may appear in some cases. A 
conclusive diagnosis ma.y be made upon finding the parasites within the 
corpuscles by microscopic exammation of the blood. 

A fatal termination is usually reached mthin three or four days. If 
recovery occurs, it is much prolonged, due to the time required for the 
generation of new corpuscular elements to replace those destroyed. 

The Chronic Type. — The difference in the symptoms of the chronic 
type of the disease from those of the acute is one of degree. Further, 
there is a seasonal difference, the milder chronic form usually appearing 
in the late fall and early winter, the acute in the hot summer months. 
The temperature does not go as high, remaining at about 103° F. and 



350 PARASITES OF THE DOMESTIC ANIIVL\LS 

not exceeding 105° F. The anaemic condition is indicated by tiie paleness 
of the visible niucoste, and the extended course brings about great 
emaciation. In these cases hemoglobin is not usually passed with the 
urine, hence hemoglobinurca or "red water," typical of the acute form, 
is absent. 

Death rarely occurs in this type of the disease, though, due to its 
prolonged course and the excessive loss of flesh, much loss is sustained 
in the productive valuation of the animal. 

Prevention and Treatment. — Prevention is by measures dealing 
with the cattle tick Manjaropus annulatus, which is the specific carrier 
and transmitter of the protozoan causing the disease. As study of the 
life history of this tick has shown that it will not mature except upon a 
bovine or efjuine host, it follows that it can be exterminated from in- 
fested iii-eniises b.y keeping cattle and horses off of such premises until 
the larval ticks, unable to find a host, have perished. With this purpose 
in view, systems of pasture rotation have been devised additional to 
methods directed toward the destruction of ticks on the cattle (Ref. 
Margaropiis annulatus, p. 145). 

Medical treatment of animals sick with Texas fever has not proved 
satisfactory. In the milder type of cases the constipation may be re- 
lieved somewhat by Epsom salts. Repeated doses of digitalis during 
the excessive anaemia and the administration of tonics, such as gentian 
and nux vomica, dining the stage of convalescence, have been recom- 
mended as beneficial. The recovering animal should have free access 
to jiurc watei- and a generous supply of nutritious food. 

Order III. Sarcosporidia 

Sporozoa (p. 336). — The Sarcosporidia are parasites in striated 
muscle cells of vertebrates. Sporulation takes place during the develop- 
ment of the tro]ihozoite which becomes surrounded liy a protective 
envelope. 

These muscle parasites are found in man, in domestic and wild birds, 
and are common in domestic mammals. The muscles more commonly 
invaded are those of the upper part of the esophagus, larynx, the body 
wall, the diajihragm, and the psoas muscles. 

Development. — Within the muscle fiber the parasite first appears as 
a minute boily in which stage it is known as Miescher's tube. As the 
yoinig ti-ophozoite develops it becomes multinuclear and surrounded by 
a membrane, while groups of spores form in the center of the proto- 
l^lasmic body. With the continuation of the spore formation the cyst 
enlarges, causing such distension of the muscle fiber as to result in its 
rupture, releasing the cyst which ultimately bursts, the spores thus 
becoming scattered to infest new muscle cells. By repetitions of this 



THE PROTOZOAN SUBGROUPS 



351 



auto-infective process the entire skeletal musculature may become 
affected. More or less destruction of muscle tissue is thus brought 
about which necessarily is relatively injurious to the host; furthermore, 
the eifect is contributed to by the extremely toxic nature of the parasites 
themselves. 

Importance of Sarcosporidiosis and Mode of Infection. — Hosts show- 
ing high incidence of infection with Sarcosporidia among domestic 
animals are pigs, sheep, cattle, and horses, the infecting species in each 
case being Sarcocystis miescheriana occurring in pigs, S. ienella in sheep, 





Fig. 172. — Various forms of Sarcosporidia. — 2. Sarcocystis blanchardi. Longidtudinal 
section of an infected muscle with young individual (after Crawley, from Doflein, from 
VanEecke, Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 3. Sarcocystis tenella in a 
Purkinje cell of the heart of a sheep (after Crawley, from Doflein, from Schneidemuhl, 
Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 4. Sarcocystis tenella in the wall of the 
esophagus of a sheep (after Crawley, from Dofiein, from Schneidemuhl, Cir. No. 194, Bu. 
An. Ind., U. S. Dept. Agr.). 5. Sarcocystis muris in muscles of mouse (after Crawlev, 
Cir. No. 194, Bu. An. Ind., U. S. Dept. Agr.). 

S. blanchardi in cattle, and S. bertrami in horses. In these animals the 
infection has been considered as of little pathologic importance; the 
sarcosporidiosis is apparently never fatal, and it is rare to find an animal 
visibly .affected. This conclusion, however, may be modified somewhat 
by further studj' of the parasite, warranted by its prevalence, toxicity, 
and ]iossibly greater pathologic import than at present supijoscd. 
Up to the present lime little has l)Ocn brought to light as to the life his. 



352 PARASITES OF THE DOMESTIC ANBIALS 

tory of the Sarcosporidia or as to the mode by which they infect. They 
are known to be fatal to mice, and it has been found that when mice are 
fed upon the flesh of other mice containing Sarcosporidia they become 
infected. Hence the conckision follows that natural transmission occurs 
in these animals through their habit of nibbling at their dead; but this 
method of transfer can hardly be considered in the case of sheep, cattle, 
and horses, and the mode of infection in these animals remains a prob- 
lem. 

In an article upon the Sarcosporidia encountered in Panama (Journal 
of Parasitology, March, 1915), Darling suggests that these muscle 
parasites of vertebrates are aberrant forms of the Neosporidia of in- 
vertebrates, and points to the facility with which herbivora may in- 
gest Neosporidia with leaves and other vegetation bearing infected 
invertebrates and their droppings. "Is it not possible," Darling writes, 
"that Sarcosporidia may be sidetracked varieties of some of the Neo- 
sporidia of invertebrates which have invaded the musculature of a 
hospitable though by no means definitive host and are unable to con- 
tinue further their life cycle and escape from a compromising and aber- 
rant position?" The high incidence of infection among sheep, cattle, 
hor.ses, and swine is evidence favoring this explanation. 



GLOSSARY 

Aberrant. In botany and zoology, differing in some of its characters from the group 

in which it is placed. 
Acari. Arthropods of the order Acarina; mites and ticks. 
Acaricide. A medicinal agent used to destroy acari. 
Agamous. In zoology, having no distinguishable sexual organs. 
Amorphous. Without definite form; shapeless. 
Ambulatory. Formed or adapted for walking. 
Ametabolic. Pertaining to insects and other animals which do not undergo a 

metamorphosis. 
Anorexia. Loss or absence of appetite. 

Antenna. A segmented process on the head of insects, myriapods, and crustaceans. 
Anthelmintic. A medicinal agent used to destroy or expel worms from the intestinal 

tract. 
Apodal. Without feet. 
Apterous. Without wings. 
Aquatic. Growing in or frequenting water. 
Arboreal. Attached to or frequenting trees. 
Arista. A tactUe filament at the end of the antenna of an insect. 
Article. A segment or part of the body coimected by a joint with another segment 

or part. 
Asexual. Having no sex. 

Basis capituli. Basal portion of the capitulum or head of a tick. 
Bitid. Cleft or divided into two parts. 

Bisexual. Having the organs of both saxes in one individual. 
Buccal. Pertaining to the cheeks or mouth cavity. 
Budding. A method of reproduction by which a protuberance from the parent 

organism develops into a new organism. 
Bursa. A sac or sac-Uke cavity. 
Capitulum. The head of a tick. 

Caryozoic. Pertaining to parasites which live in the cell nucleus. 
Catalepsy. Suspension of sensibility and voluntary motion. 
Caudal. Pertaining to the tail. 
Cephalic. Pertaining to the head. 

Cephalothorax. The fused head and thorax of arachnids. 

Chelae. Pincer-like terminations of certain of the limbs of crustaceans and arachnids. 
Chelate. Terminated by chelae. 
Chitin. The horny substance forming the harder part of the integument of insects 

and other arthropods. 
Cilia. Hair-like processes, as of a cell, capable of \dbratory movement. 
Coelom. The body-cavity, as distinguished from the intestiual ca\'ity; the peria.xial, 

perivisceral, or perienteric space. 
Coelozoic. Pertaining to parasites which live in the coelomic cavities of the body. 



354 GLOSSARY 

Coxa. The hip or hip joint. In insects and other artlu'opods the first segment of 
the leg from the body, articulating with the second segment or trochanter. 

Cystogenous. Producing or bearing cells. 

Cytozoic. Pertaining to parasites which live within the cell cytoplasm. 

Dentate. Having a toothed margin or tooth-like projections. 

Denticulate. Having very small tooth-like projections. 

Dimorphism. The property of assuming or of existing under two distinct forms. 

Dipterous. Having two wings; belonging to the insect order Diptera. 

Dorsum. The dorsal surface or back of an animal. 

Ecdysis. The process of casting the skin; molting. 

Elytra. The fore-wings of beetles, serving to cover the hind wings. 

Enterozoic. Pertaining to parasites which live in the lumen of the digestive tract. 

Epimeron. One of the side-pieces in the segment of an arthropod animal. 

Facet. A smooth, fiat, circumscribed surface. 

Fauna. The aggregate of the animals of a given region or geological period. 

Femur. The thigh bone. The third segment of the leg of an insect, articulating 
proximally with the trochanter and distal]\' ^\^th the tibia. 

Filiform. Thread-like. 

Fission. Reproduction by division of the body into two parts, each of which be- 
comes a complete organism. 

Flagellum. A whip-like appendage or process of a cell. 

Flora. The aggregate of the native plants of a given region or period. 

Gamete. A sexual cell or germ cell. 

Gametocyte. An adult parasite, as in the Plasmodium of malaria, when in its 
rcjjroductive form. 

Granular. Consisting of grains or granules. 

Gregarious. Inclined to gather together, as to live in flocks or herds. 

Habitat. The natural abode of an animal or plant. 

Halteres. Tlie rudimentary hind wings of Diptera; balancers. 

Haustellum. A proboscis adapted to take food by suction, as in many insects. 

Hematozoic. Pertaining to parasites which live in the blood. 

Hemelytra. The partially thickened anterior wings of certain insects. 

Hermaphroditism. The union of the two sexes in the same individual. 

Hexacanth. The sL\-hooked tapeworm embryo; the onchosphere. 

Hexapod. A sLx-footed animal; a true insect. 

Hyaline. A glassy or transparent substance or surface. 

Isiago. The final or adult stage of insects. 

Infundibuliform. Having the form of a funnel. 

Labium. In insects, the lower lip, formed by the second pair of maxillie. 

Labrum. In insects, the upper lip. 

Lobe. A somewhat rounded projection or division of an organ or part. 

Macrogamete. The large female gamete or germ cell. 

Macrogametocyte. The female gametocyte. 

Mandibles. In arthropods, the anterior pair of mouth parts which form biting jaws. 

Marine. Living in the sea. 

Maxilla;. In arthropods, paired appendages behind the mandibles, usually serving 

as accessory jaws. 
Merozoites. Asexually formed spores of the malai'ia parasite. 



GLOSSARY 355 

Mesothorax. The middle segment of the thorax of an insect. 

Metabolism. The processes concerned in the building up of protoplasm and its 

destruction. 
Metamere. One of a series of segments composing the body, as in many worms 

and in arthropods. 
Metamorphosis. Change of form or sti-ucture, as in the larval, pupal, and imago 

stages of an insect's development. 
Metaphyta. Plants consisting of many cells; all plants above the Protophyta. 
Metathorax. The posterior segment of the thorax of an insect. 
Metazoa. Animals which, in an embryonic condition, possess at least two distinct 

germinal layers; all animals above the Protozoa. 
Microgamete. The male germ cell consisting of a detached flageUiform process of 

a microgametocyte. 
Microgametocyte. The parent male cell. 

Micron. One thousandth of a millimeter; a unit of microscopic measure. 
Molting. The shedding of the hair, feathers, or outer layer of the skin, which are 

replaced by new gi'owth. 
Morphology. The science of the outer form and internal structure of animals and 

plants. 
Myasis. A disease caused by the presence of the larvse of flies in or on the body. 
Myiasis. Same as myasis. 
Myiosis. Same as myasis. 

Ocellus. A small siinple eye of many invertebrates. 
Octopod. Having eight feet, as in adult arachnids. 
Onchosphere. The tapeworm embryo; the hexacanth. 
Ookinete. Same as zygote. 
Oospore. Same as zygote. 
Operculum. A lid-lLke process or part. 
Ovum. An egg cell or egg. 
Ovigerous. Egg bearing. 
Oviparous. Producing eggs that hatch after they have passed from the body of the 

parent. 
Oviposition. ' The laying of eggs, especially applied to insects and arachnids. 
Ovipositor. A specialized organ, as in certain insects, for depositing eggs. 
Ovoviviparous. Producing eggs that have a well developed shell or covering, as in 

oviparous animals, but which incubate within the bod}' of the parent. 
Ovulation. The formation of eggs in the ovary; the discharge of the egg or eggs 

from the ovary. 
Palpi. Appendages, usually organs of touch or taste, attached to the mouth parts 

of insects and other arthropods. 
Papilla. A small nipple-like or pimple-like projection. 
Parasiticide. A remedy that destroys parasites. 
Parthenogenesis. The production of individuals from ova without fertilization by 

tlie male element. 
Pedipalpi. Leg-like or pincer-like appendages of arachnids, located on each side of 

the mouth. 
Phylogenic. Pertaining to tlie ancestral history of an animal or jilant. 
Phytozoon. A colony of animals resembling a plant. 



356 GLOSSARY 

Plasmoditun. A mass of protoplasm formed by the union of two or more amebiform 

bodies or individuals. 
Plumose. Feathery; plume-like. 

Pollenose. Bearing a powdery or pollen-like substance. 
Predacious. Living by preying on other animals. 
Prehensile. Adapted for grasping. 
Proboscis. The tubular process of the head, especially of insects and arachnids, 

adapted for sucking or piercing. 
Proglottid. The segment of a tapeworm. 
Prothorax. The anterior segment of the thorax of an insect. 
Protophyta. The division of unicellular plants. 
Protozoa. The phylum consisting of the unicellular animals. 
Pruritus. An intense degree of itching. 
Pseudopodia. Processes of the protoplasm of a cell which may be protruded or 

retracted, as for locomotion or for taking food. 
Pubescent. Arrived at puberty, or the earliest age at which the reproductive func- 
tion can be performed. 
Puparium. The ease in which an insect is enclosed between its larval stage and 

the state of full development or imago. 
Pupiparous. Pertaining to insects in wliich the young are born ready to become 

pupa?, as in the sheep tick. 
Quiescent. At rest. 

Rostellum. A. small beak or hook-like process. 
Rostrum. A beak-like process or appendage. 

Saprophyte. Any vegetable organism living on dead or decaying organic matter. 
Schizogenesis. Reproduction by fission. 
Schizogony. Same as schizogenesis. 
Schizont. A malaria parasite of the asexual generation. 
Scolex. The head of a tapeworm, either in the larval or adult stage. 
Scutum. The dorsal shield or plate, present in certain ticks. 
Serrate. Notched or toothed on the edge. 
Somatic. Pertaining to the body as a whole. 
Somite. One of the longitudinal segments into which the body of annelid worms, 

arthropods, and vertebrates is divided. 
Spiracle. A breathing orifice, as in the tracheal openings of insects. 
Spore. A germ or seed of one of the lower animals or plants. 
Sporocyst. A case or cyst containing many spores. 
Sporogenesis. Reproduction by means of spores. 
Sporogony. Same as sporogenesis. 
Sporozoite. One of the young active spores of a sporozoan produced by division of 

the passive spores contained in the sporocyst. 
Sporulation. Spore formation. 
Stigmata. Small spots or marks; usually applied to the respiratory openings of 

insects; spiracles. 
Strobila. An adult tapeworm. 
Suctorial. Adapted for sucking. 
Tarsus. In insects, the small segments forming the distal termination of the leg 

and articulating with the tibia. 



GLOSSARY 357 

Tergiun. In zoology, the back. 

Terrestrial. Of or inhabiting the land or ground in distinction from trees, water, etc. 

Tibia. In insects, the fourth segment of the leg, articulating proximally with the 

femur and distally with the tarsi. 
Tracheae. The air-conveying tubules forming the respiratory system of insects and 

other arthi'opods. 
Trenchant. Sharp; cutting. 
Trochanter. In insects, the second segment of the leg, articulating proximally with 

the coxa and distally with the femur. 
Vacuole. A cavity or vesicle in cell protoplasm. 
Vermicide. A substance which kills worms; a drug to kill parasitic worms of the 

intestines. 
Vermifuge. A medicine that expels worms from the bodies of animals. 
Verminous. Infested with worms, or caused by worms, as verminous diseases. 
Viviparous. Producing living young by true birth, as in mammals, and not by 

hatching from eggs, as in oviparous and ovoviviparous animals; often applied 

to the bringing forth of young which have been hatched from eggs within the 

body of the parent. 
Zoophyte. Same as phytozoa. 
Zygote. The encysted stage of certain sporozoans after fertilization by a sperm 

cell and before division into spores. 



INDEX 



Acanthia lectularia, 90 
Acanthocephala, 217, 224, 306 
Acariasis, 96 
Acarina, 94 

parasitism of, 95 
Ades calopus, 29 
Agriostomum, 280 
Ainblyonima, 142 

americanum, 145 
Ameba, 312, 324 

budding, 313 

ectoplasm, 312 

encystation, 313 

endoplasm, 312 

fission, 313 

method of feeding, 313, 324 

morpliologic characteristics, 312 

motility, 312, 324 

nucleus, 313 

pseudopodia, 312, 324 

reproduction, 313, 324 

respiration, 313 

streaming of cytoplasm, 312, 313, 
324 

vacuoles, 312, 313 
Ameba meleagridis, 325 
Amebic dysentery, 326 

in man, 326 
American dog ticlv, 143 
Amphistoniidae, 157, 167 
Amphistomum cervi, 167 
Ankylostoma, 280 

canina, 291 

duodenale, 292 
Anlcylostomeaj, 280 
Ankylostomiasis, 291 
Anlcylostomum stenocephahmi, 292 



Amielida, 224, 307 
Anopheles, 26, 320 

maeulipennis, 26 

punctipennis, 28 

quadrimaculatus, 26 
Anoplocephala niamillana, 175 

perfoUata, 174 

plicata, 175 
Anthelmintics, use and action 

of, 221 
Apterous insects, 18 
Arachnida, 94 

classification of, 96 
Arduenna, 228 

strongylina, 251 
Arduenninae, 228 
Argasidae, 97, 139 
Argas americanus, 139, 327 

miniatus, 139, 327 
Arthropoda, The, 13 

circulatory sj^stem, 14 

digestive system, 14 

excretory organs, 14 

musculature, 14 

nervous system, 14 

reproduction, 15 

respirator)' system, 14 

sense organs, 15 

structure in general, 13 
Arthropoda as transmitters of infec- 
tious diseases, 313, 315 
Arthropoda, parasitic subgroups of 15 
Ascariasis, 229, 231 

importance of treatment, 233 

location of wonns, 229. 232 

occurrence, 231 

liathoocnio iufiucuccs. 232 



360 



INDEX 



Ascariasis of tlie cat, 237 

occurrence, 239 

treatment, 239 
Ascariasis of the dog, 237 

occurrence, 238 

post-mortem appearance, 239 

treatment, 239 
Ascariasis of tlie liog, 239 

effect, 240 

treatment, 241 
Ascariasis of tlie horse, '. 33 

control, 234 

etiologj', 234 

occurrence, 233 

sjTnptoms, 233 

treatment, 234 
Ascariasis of the ox, 241 
Ascariasis of the sheep, 241 
Ascariflffi, 222, 229 

parasitism of, 229, 231 
Ascaris, 225, 229 

equi, 233 

equorum, 233 

lumbricoides, 229, 239 

marginata, 237 

megalocephala, 233 

mystax, 237, 239 

o\'is, 229, 239 

suis, 229, 239 

suum, 229, 239 

vitulorum, 241 
Ascaroidea, 225 

Auricular mange of the cat, 118 
Auricular scabies of the rabbit, 118 

B 

Bacillary white diarrhea of chicks, 345 
Bacterium ]3ullorum, 345 
Bathmostomum, 281 
Bedbug, The 8, 90 

as a pest of poultry, 90 

control, 92 

effect of bite, 90 



habits, 90 

reproduction and development, 90 
Beef measles, 174, 194, 195 

degeneration of cyst, 198 

development, 197 

federal regulations in regard to, 199 

influence of temperature, 198 

location and a]3pearance, 197 

method of infection, 197 

occurrence, 196 

vitality of larvse, 198 
Beef and pork tajjewonn, methods of 

differentiation, 200 
Beef tapewoim, 170, 195 
Belascaris marginata, 237 

mystax, 237, 239 

cati, 237, 239 
Bilharzia bo vis, 168 

crassa, 168 
Bilharziosis, 168 
Black gnat, 31 
Blackhead of turkeys, 325 
Black horse fly, 35 

as a transmitter of disease, 36 

effect, 35 

life history, 35 

protection from, 36 
Blood fluke, 168 
Blow fly, 50, 52 

effect, 53 

reproduction and development, 52 
Bluebottle fly, 52 
Body louse, 79 
Body mange of poultry, 132 
Boophilus, 142 

annulatus, 144, 145, 314, 347 

bovis, 144, 145, 314, 347 

decoloratus, 316 
Bot flies, 53 
Bot, horse, 5, 53, 57 
Bothriocephalus latus, 185 
Brachiopoda, 155 

Bronchial and pulmonary strongylosis 
of cattle, 259 



INDEX 



361 



control, 264 

course, 260 

development, 263 

etiology, 263 

post-mortem appearance, 262 

prognosis, 260 

symptoms, 259 

symptoms, duration of, 260 

treatment, 265 
Bronchial and pulmonary strongylosis 
of the horse, 261 

occurrence, 261 

symptoms, 261 
Bronchial and puhnonary strongylosis 
of the pig, 260 

occurrence, 260 

symptoms, 260 
Bronchial and pulmonary strongylosis, 
post-mortem appearance, 262 

control, 264 

development, 263 

etiology, 263 

treatment', 265 
Bronchial and pulmonary strongylosis 
of the sheep and goat, 256 

control, 264 

course, 259 

development, 263 

etiology, ^63 

post-mortem appearance, 262 

prognosis, 259 

symptoms, 258 

treatment, 265 
Buffalo gnat, 31, 32 

control, 33 

effect, 33 

life history, 32 

occurrence, 32 

protection from, 33 

treatment, 34 
Brazilian septicemia of fowl, 327 
Bruce, investigations of, 45, 315, 330 
Bryozoa, 155 
Bunostomeas, 281 



Bunostommn trigonocephalum, 293 
phlebotomum, 293 



Calliphora vomitoria, 52 
Cardiac filariasis of the dog, 248 
Cardio-pulmonary strongylosis of the 
dog, 261 

post-mortem appearance, 263 

symptoms, 262 
Castor-bean tick, 143 
Cattle tick, 144, 145, 314, 347 
Cestoda, 159, 169 
Chabertia o^ana, 287 
Chiggers, 96, 99 
Chloroform as treatment for lung 

worms, 266 
Choanotaenia infundibulifomiis, 189 
Chorioptes, 103 

parasitism, 103 

species, 103 
Chorioptes conmiunis, 103 

var, bovis, 113 

var. equi, 108 

var. ovis, 112 
Chorioptic scabies of cattle, 1 13 

course, 113 

location, 113 

treatment, 120, 130 
Chorioptic scabies of the horse, 108 

course, 108 

diagnosis, 109 

lesions, 109 

prognosis, 109 

sjanptoms, 108 

transmission, 109 

treatment, 120, 129 
Chorioptic scabies of the sheep, 112 

course, 112 

prognosis, 112 

sjTuptoms, 112 

transmission, 112 
Chrysonijna macellaria, 50 



362 



INDEX 



Cimex lectularius, 00 
CiniicidsB, 22, 90 
Cittotsenia denticuUita, 185 
Classification of the Arachnida, 96 
Classification of the ishylum Ccelhel- 

minthes, 222 
Classification of Insects, 20 
Classification of the phylum Platy- 

hehiiinthes, 157 
Classification of the plylmii Protozoa, 

322 
Cnemidocoptes, 103. 132 

species of, 103, 132 
Cnemidocoptes gallina, 103, 133 

mutans, 103, 132 
Coccidia, 322, 323, 337 

infection, 337 

life cycle, 322, 337 

jsarasitism, 337 

pathogenicity, 337 

reproduction, 337 
Coccidial enteritis of chicks, 345 

control, 346 

diagnosis, 345 

differentiation from hacillar>- white 
diarrhea, 345 

infection, 34G 

post-mortem a|)])earance, 345 

sTOiptoms, 345 
Coccidiosis of the dog, 342 

investigations by Hall and Wigdor, 
342 
Coccidiosis of cattle, 343 

of cliicks, 345 

of the dog, 345 

of man, 342 

of the rabbit, 342 
Coccidium cuniculi, 342 

oviforme, 342 

tenellum, 345 

zurni, 343 
Cochliomyia macellaria, 50 
Coelhehninthes, 216 

classification of, 156, 216, 222 



Ccelom, 216 

Coenurosis, 204 

Coenurus, 173, 194, 204, 205 

Colic, thrombo-embolic, 2SS, 290 

Conunensalism, 2, 7- 

example of, 2, 7 
Compsomjia macellaria, 50 
Connective tissue mite of poultry, 

134 
Cooperia curticei, 268 

oncophora, 275 
Cryptobia, 329 
Cryptocystis, 178, 195 
Ctenocephalus canis, 65, 79 

felis, 65 
Culex and Anopheles, differentiation, 

28 
Culex pungens, 26, 28 
Culicids, 20, 24 
Cylicostomeae, 281 
Cylicostomum, 28 1 
Cysticercoid, 173, 178, 195 
Cysticercosis, 174, 195 
Cysticercus, 173, 174, 194, 195 

bovis, 174, 195, 197 

cellulosffl, 174, 195, 199, 202 

ovis, 203 

tenuicollis, 174, 179, 195, 203 

trichodectes, 79, 178, 183 
Cytoleiehida^, 134 
Cytoleichus nudus, 134 

D 

Davainea cesticilhis, 190, 191 

echinobothrida, 191 

proglottina, 189 

tetragona, 190, 191 
Degeneration, parasitic, 3, 4 
Demodecidae, 96, 97, 103 
Demodectic mange, 96, 104 

of the dog, 116 

of the hog, 115 

of the sheep, 112 



INDEX 



363 



Demodex folliculorimi, 104 

var. canis, 104, 116 

var. ovis, 104, 112 

var. suis, 104, 115 
Depluming mange of poultry, 133 
Depluming mite, 101, 133 
Dennacentor, 142 

electus, 143 

occidentalis, 143 

reticulatus, 143 

variabilis, 143 
Dibotliriocephalus latus, 185 
Dibothrium latum, 185 
Dicroccelium lanceatimi, 160, 163 
Dictyocaulus arnfieldi, 261 

filaria, 221, 256 

■\dviparous, 259 
Dioctophjone renale, 296 
. visceralis, 296 
Diphyllobothriasis, 185 

occurrence, 186 
Diphyllobothriida;, 160, 185 
Diphyllobothrium latimi, 185 
Diplospora bigemina, 342 
Dipping vats, 126 
Dips, 48, 120, 125 
Diptera, 18, 20 

parasitic families of, 23 

parasitif3m of, 23 
Dipterous insects, IS, 23 
Dipylidium caninum, 68, 79, 178, 181, 

183 
Dirofilaria immitis, 221, 248 
Dispharagus hamulosus, 254 

nasutus, 254 

spiralis, 254 
Distomea;, 156, 157 
Distomiasis, 157, 163, 165 

of cattle, 166 

of tlie sheep, 165 
Distomum americanum, 160 

hepaticmn, 160 

lanceolatmn, 160 

magnum, 160 



Dochmiasis, 291, 292 
Dochmius cernuus, 293 

radiatus, 293 

stenocephalus, 292 

trigonocephalus, 291 
Docopliorus C3'gni, 86 

icterodes, 84 
Dourine, 333 

control, 336 

federal control of outbreaks, 333 

infection, 333, 334 

stages in, 334 

symptoms, 334 
Drepanidotaenia infundibuliformis, 189 
Dysentery of cattle, 343 

E 

Earthworm, 216 
Ecdysis, 13 

Echinococcosis, 183, 210 
Echinococcus, 173, 181, 183, 194, 210 

alveolaris, 212 

granulosus, 181, 183, 184, 194, 210 

multilocularis, 210, 212 

pohanorphus, 181, 183, 210 
EchinorhTOchus gigas, 306 
Ectozoa, 9 
Eimeria avium, 345 

stieds, 342 
El dourine, 333 
Endoparasites, 9 
Entameba, 326 

coU, 326 

histolytica, 326 
Entero-hepatitis of turlveys, 325 
Entozoa, 9 
Erratic parasites, 8 
Esophageal and gastric filariasis of the 
dog, 250 

course, 251 

develoimient, 251 

occurrence, 250 

patliogenesis, 250 



364 



INDEX 



sjTiiptoms, 251 

treatment, 251 
Esophageal filariasis of cattle, 246 

of the dog, 250 

of the sheep, 246 

of the horse, 247 
European dog tick, 143 
Eustrongj'lida;, 224, 296 
Eustrongylosis, 296 

occurrence, 296 

symptoms, 297 

treatment, 298 
Eustrongylus gigas, 296 

visceralis, 296 
Exoparasites, 9 



Fasciola amcricana, 160, 163 

hepatica, 5, 160 

lanceolata, 160, 163 

magna, 160, 163 
Fasciola hepatica, life history of, 5, 160 
Fasciola lanceolata, life history of, 163 
Fasciola magna, life history of, 163 
Fascioliasis, 157, 163, 165 
Fascioliasis of cattle, 166 

control, 167 

sjTiiptoms, 166 

treatment, 168 
Fascioliasis of the sheep, 105 

control, 167 

course, 165 

prognosis, 166 

symptoms, 165 

treatment, 168 
Fasciolidae, 157, 160 
Filaria, 227 

bancrofti, 249 

cer\'ina, 248 

equina, 244 

immitis, 248 

labiato-iiapillosa, 248 

sanguinis hominis, 249 

sanguinolenta, 250 



Filarise of cattle, 246 

of the dog, 248 

of the hog, 251 

of the horse, 244 

of poultrj', 254 

of the sheep, 246 
Filariasis of cattle, 246 

effect, 247, 248 

occurrence, 247, 248 
Filariasis of the deer, 248 
Filariasis of the dog, 248 

diagnosis, 249, 251 

occurrence, 248, 250 

pathogenesis, 249, 250 

theories as to infection, 249 

treatment, 250, 251 
Filariasis of the hog, 247, 251 

control, 253 

occurrence, 252 

treatment, 254 
Filariasis of the horse, 244 

effect, 245, 246 

occurrence, 244, 245, 246 

treatment, 246 
Filariasis of poultry, 254 
Filariasis of the sheep, 246 

effect, 247 

occurrence, 247 
Filariidae, 222, 244 

parasitism of, 244 
Filarioidea, 227 
Fixed parasites, 8 
Flagellata, 322, 326 
Fleas, 65 

as carriers of disease, 66 

control, 68 

habits, 66 

household infestation, 69 

reproduction and development, 
65, 66 

species, differential characters of, 65 

treatment, 68 

usual hosts, 66 

vitality, 68 



ESTDEX 



365 



Flesh flies, 50, 52 

protection from, 52 

reproduction and development, 52 
Flies, 11, 23, 35 
Fluke, liver, 5, 156, 160, 163 
Fly, house, 11, 37, 189 
Follicular mange of the dog, 116 

course, 116 

symptoms, 116 

transmission, 117 

treatment, 130 
Follicular mange of the hog, 115 

occurrence, 115 

treatment, 130 
FoUicular mange mite, 103 
Follicular mange of the sheep, 112 

location, 112 

prevalence, 112 
Forked worm of fowl, 293 
Fowl septicemia, 327, 345 
Fowl tick, 139 

control, 140 

development, 140 

effect, 140 

habits, 140 

occurrence, 140 
Fumigation treatment in verminous 
bronchitis, and pneumonia, 265 

G 

Gaigeria, 281 
Gamasidae, 96, 98 
Gamasid mites, 96, 98 
Gastric filariasis of the dog, 250 
Gastric filariasis of the horse, 245, 246 
Gastric and intestinal filariasis of the 

hog, 251, 252 
Gastro-intestinal strongylosis of cattle, 
272 

control, 276 

development, 276 

etiology, 276 

occurrence, 275 



pasture rotation, 277 

post-mortem appearance, 275 

symptoms, 275 

treatment, 277 
Gastro-intestinal strongjdosis of the 

goat, 268 
Gastro-intestinal strongylosis of the 
sheep, 268 

control, 276 

development, 276 

etiology, 276 

occurrence, 271 

pasture rotation, 277 

pathogenesis, 272 

post-mortem appearance, 275 

symptoms, 272 

treatment, 277 
Gastrophilus equi, 5, 53 

hemorrhoidaUs, 57 

intestinalis, 5, 53 
Gid of cattle, 205, 209 
Gid of the sheep, 204 

the ccBnurus, 205 

control, 209 

development, 206 

occurrence, 205 

post-mortem appearance, 207 

symptoms, 208 

treatment, 209 
Gigantorhj'nchus hirudinaceus, 306 
Glossary, 353 
Glossina, 44, 314 

longipalpis, 44, 46 

morsitans, 44, 46, 330 

palpahs, 44, 46 
Gnat, buffalo, 31, 32 
Gnathobdelhdffi, 224, 308 
Gnats, 31 
Gongylonema, 227 

scutata, 246 
Gongyloneminte, 227 
Goniocotes abdomiualis, 82 

compar, 86 

gallinjp, 82 



366 



INDEX 



gigas, 82 

hologaster, 82 
Goniodes thimicornis, 86 

stj'lifer, S4 
Granimoceplialus, 281 
Green-lipad fly, 36 
Gyalocei)hahis, 281 

H 

Habroneiua lucgastonia, 245 * 

microstoma, 246 
Hsemaphysalis, 142 
Ha?matobia serrata, 41 
Ha-matopinus asini, 73 

eun-stcrnus, 74 

macroccjiluilus, 73 

suis, 77 

urius, 77 
Hsemonchu.s contortus, 26S 
IIa?moi5is saiiguisuga, 308 
Harvest mites, 99 

effect, 100 

habits, 100 

jirotect ion from, 100 

treatment, 100 
Heel fly, 57 
Helminthes, 9 
Helotism, 7 
Hematic filariasis of the dog, 248 

diagnosis, 249 

occurrence, 248 

pathogenesis, 249 

theories as to infection, 249 

treatment, 250 
Hematic filariasis of man, 249 
Hemiptera, 22, 89 
Hemosporidia, 323, 347 

difference in m de of infection from 
Coccidia, 337, 347 

relationship to other groups, 336, 
347 

relative pathologic importance, 347 
Hepatic coccidiosis of rabbits, 342 



Herpetomads, 316 

experiments with, 316 
Herpetomonas donovani, 316 
Heterakiasis of poultrj', 242 

sj-mptoms, 243 

treatment, 243 
Heterakida>, 222, 242 
Heterakinse, 226 
Heterakis, 226 

iniiexa, 242 

papillosa, 242 

perspicillum, 242 

vesicularis, 242 
Heteroxenous jiarasites, 8 
Hippoboscidae, 21, 47 
Hirudinea, 224, 307 
Hirudo medicinalis, 309 
Hook womi, 291, 292 
Horn fly, 41 

control, 43 

effect, 42 

habits, 41 

life history, 41 

occurrences, 41 

Ijrotection from, 43 
Horse bot flies, 5, 53 

effect of bots, 55 

habits, 53 

life history, 54 

treatment, 56 
Horse leech, 308 

effect, 309 

mode of infestation, 309 

occurrence, 309 

treatment, 309 
House fly, 11, 37, 189 

as a transmitter of infectious dis- 
eases, 11, 38, 189 

control, 38 

habits, 38 

life history, 37 

longevity, 37 

protection from, 38 
Hyalomma, 142 



INDEX 



367 



Hydatid disease, 173, 181, 183, 194, 210 

control, 214 

development, 212 

the echinococcus, 210 

longe^'ity of cyst, 213 

occurrence, 210 

post-mortem appearance, 213 

symptoms, 214 
Hymenolepis carioca, 190, 191 
Hymenoptera, 18 
Hypodemia bovis, 58 

lineata, 57 

I 

Imago, The, 19 
Incidental parasites, S 
Infectious entero-hepatitis of turkeys, 
325 

control, 326 

course, 325 

infection, 325 

post-mortem appearance, 325 

sjTiiptoms, 325 

treatment, 326 
Insecta, 15 

classifieation of, 20 
Insects, 15 

development, 18 

duration of life, 19 

growth, i9 

larviB, 18 

metamorphosis, 18 

mouth parts, 16 

parasitic subgroups, 20 

reproduction, 18 

structure, 15 
Internal parasites, 155 
Intestinal strongylosis of the cat, 291 

of cattle, 272, 285 

of the dog, 291 

of the goat, 268, 281, 287 

of the hog, 287 

of the horse, 288 

of the sheep, 268, 281, 287 



Intratracheal injections, 265 
Introduction, 1 
Isospora bigemina, 342 
Itch mites, 101 
Ixodes, 142 

hexagonus, 143 

ricinus, 143 
Ixodida;, 96, 97, 136, 141 
Ixodoidea, 96, 97, 136, 139 



Kala-azar, 316 

Kerosene emulsions, 48 

Kerosene in mosquito control, 25, 

31 
Kidney worm of the dog, 296 
Kidney worm of the hog, 295 



Laminosioptes cj-'sticola, 134 
Larvas, dipterous, 50 
Larvae, insect, IS 
Leeches, 216, 307 
Leg mange of poultry, 132 
Leishmania donovani, 316 
Leptus autumnalis, 100 
Lice, 70 

biting, 71 

sucking, 70 
Lice of poultry, 82 

control, 8S 

occurrence, 82 

treatment, 88 
Life, degeneracy in mode of, 1 
Life histoiy of beef tapeworm, tabular 

review, 172 
Life histories of dog tick and Texas 

fever tick compared, 151 
Life history of Echinococcus granu- 
losus, tabular review, 213 
Life history of gid tapeworm, tabular 
review, 207 



368 



INDEX 



Life history of horse botfly, tabular 

review, 55 
Life history of liver fluke, tabular 

re\-iew, 163 
Life history of sheep botfly, tabular 

re\ie\v, 63 
Life history of Trichinella spirahs, 

tabular review, 303 
Lime and sulphur dips, 122, 125 

method of preparing, 125 
Linguatula rhinaria, 94, 153 
Lin.uatulida, 153 
Linguatulidse, 97 
Linognatlius pedalis, 76 

pihferus, 7S 

stenopsis, 77 

\ntuli, 74 
Liotheidae, 22, 71 
Lipeurus anatis, 84 

bacillus, S6 

cajjonis, 83 

cohimbse, 86 

heterographus, 83 

meleagridis, 84 

polytrapezius, 84 

squalidus, 84 

variabilis, 83 
Lissoflagellata, 328 
Liver flukes, 5, 156, 160 

infection, 160, 164 

life history, 5, 160 

losses from, 162 

migrations and pathogenesis, 164 

prevalence, 162 

prevalence in United States, 164 
Lobosa, 322, 324 
Lone star tick, 145 
Lousiness, 71 
Lung worms, 256 

control, 264 

development, 256, 263 

method of infection vnth, 256, 
263 
Lj'perosia irritans, 41 



M 

Maladie du coit, 333 

Malaria, 26, 318 

Malaria, latent, 322 

Malaria organisms, the asexual cycle, 

318, 319 
the gametocytes, 319 
liberation of the merozoites, 319 
the macrogametocyte, 319 
the merozoites, 319 
the microgametes, 319 
the microgametocyte, 319 
relation of liberation of merozoites 

to chill, 319 
repeating of cycle, 319 
the schizont, 319 
the signet ring stage, 319 
the s])orozoites, 319, 320 
Malaria organisms, life history, 318 
Malaria organisms, the parthenoge- 

netic phase of, 322 
Malaria organisms, the sexual cycle, 

320 
fertilization of the macrogamete, 

320 
fonnation of cyst, 320 
fonnation of macrogamete, 320 
fonnation of the microgametes, 

320 
fonnation of the sporoblasts, 320 
formation of the sporozoites, 320 
liberation of the sporozites, 320 
the microgametoblast, 320 
migration of ookinete, 320 
the ookinete or zj'gote, 320 
passage of sporozoites to salivary 

glands of mosquito, 320 
relationship of anopheline mosquito 

to, 26, 313, 319, 320 
Mai de caderas, 332 
infection, 333 
occurrence, 332 
symptoms, 332 



INDEX 



369 



Mallophaga, 21, 71 
Mange, 96, 101, 102, 103, 104, 112, 
113, 114, 115, 116, 117, lis 

cnemidocoptic, 132 

foUicular, 102, 112, 115, 116 

notoedric, US 

sarcoptic, 102, 104, 112, 114, 121 
Mange of the bodj' of poultry, 
133 

course, 133 

symptoms, 133 

treatment, 133 
Mange of the cat, 117 

course, 118 

diagnosis, 118 

treatment, 120, 123 
Mange of cattle, 114 

treatment, 120, 124 
Mange of the dog, 115, 116 

course, 115, 116 

lesions, 115, 116 

symptoms, 115, 116 

transmission, 115, 117 

treatment, 120, 123, 130 
Mange of the goat, 113 

treatment, 120, 124 
Mange of the hog, 114, 115 

symptoms, 114, 115 

transmissions, 114- 

treatment, 120, 122, 130 
Mange of the horse, 104 

control, 122 

development, 105 

diagnosis, 105 

lesions, 105 

prognosis, 107 

symptoms, 104 

transmission, 107 

treatment, 120, 121 
Mange of the legs of poultry, 132 

course, 132 

sjanptoms, 132 

treatment, 132 
Mange mites, 96, 103, 132, 134 



Mange of poultry, 132, 134 
Mange of the rabbit, 118 

treatment, 120, 124 
Mange and scab mites, 96, 101, 102, 
103, 117, 132, 134 

development, 101, 103 

reproduction, 101, 103 
Mange of the sheep, 112 

treatment, 120, 124 
Margaropus, 142, 145 

annulatus, 144, 145, 314, 347 
Mastigophora, 322, 326 
Measles, 174, 194, 195 

ofman, 174, 194, 195 

of the ox, 174, 195 

of the pig, 174, 195 

of the sheep, 174, 195 
Medicinal leech, 309 
Melophagus ovinus, 4, 47, 76 
Menopon biseriatum, S3 

pallidum, S3 
Menopum biseriatmn, 83 

pallidmn, 83 

trigonocephalmn, S3 
Metamorphosis, insect, 19 

complete, 19 

incomplete, 19 
Metastrongylidae, 227 
Metastrongylina;, 223, 256 

life history, 256, 263 
Metastrongylus, 227 
Metazoa, 311 
Miescher's tube, 350 
Mites, 94 
Molluscoidea, 155 
Molting, 13 
Moniezia alba, 176 

denticulata, 185 

expansa, 176 

planissima, 176 
Monoxenous parasites, S 
Mosquitoes, 11, 24 

breeding habits, 24 

control, 31 



370 



INDEX 



Culex ami Anojiheles, difl'ereiitia- 
tion, 28 

development, 25 

effect upon live stock, 31 

larvte, 24 

pathologic importance, 26 

protection against, 31 

pupse, 25 

range, 24 

relationshij) to filariasis, 26 

relationship to malaria, 26, 313, 320 

relationship to yellow fever, 26, 29 
Multiceps gaigeri, ISl 

multiceps, 170, 194, 204, 206, 207 

serialis, 179 
Musca (lomestica, 1 1, 37, 1.89 

voniitoria, 52 
IMuscidffi, 20, 37 
Mutualism, 2, 7, 

example of, 2, 7 
Myasis, 50 

N 

Nagana, 45, 314, 330 

etiology,45, 314, 330 

investigations by Bruce, 45, 314, 
330 

occurrence, 330 
Nemathelniinthes, 155, 216, 222 
Nematoda, 217, 222, 
Nematode woims, parasitism in gen- 
eral, 219 

adaptability to changed en\'iron- 
ment, 221 

factors influencing injury to host, 
220 

host limitations, 220 

infection, 219, 220 

treatment in general, 221 
Nematodirus filicollis, 273 
Neosporidia, 336, 350 
Net tick, 143 
Nodular disease, 281 



Nodular strongylosis of cattle, 285 

of the goat, 281 

of the hog, 287 
Nodular strongylosis of the sheep, 281 

development, 283 

importance, 284 

occurrence, 283 

post-mortem appearance, 284 

sjTnptoms, 284 

treatment, 285 
Notoedres, 101, 117 

var. cati, 117, 118 

var. cuniculi, 118 

parasitism of, 103 
Notoedric mange, treatment of, 120, 
123, 124 





Obligate parasites, 8 

Ocular filariasis of the horse, 245 

of the ox, 248 
nilsophagostomese, 280 
Qisophagostomiasis of cattle, 285 

of the goat, 281 

of the hog, 287 

of the sheep, 281 
CEsophagostomum, 255, 280 

colmnbianum, 281 

dentatum, 287 

inflatum, 285 

radiatum, 285 

subulatum, 287 

venulosum, 282 
(Estridffi, 21, 53 
Oilstrus oris, 62 
Optional parasites, 8 
Organic multiplication, influences re- 
stricting, 1 
Ornithobius bucephalus, 86 
Ornithodorus megnini, 140 
Omithonomus cygni, 86 
Ostertagia marshalli, 269 

ostertagi, 272 



INDEX 



371 



Otacariasis of the cat, IIS 
occurrence, 118 
treatment, 131 
Otacariasis of the dog, 117 

occurrence, 117 

prognosis, 117 

symptoms, 117 

treatment, 131 
Otacariasis of the rabbit, 118 

course, 118 

sjTnptoms, 119 

treatment, 131 
Otobius megnini, 159 
Otodeotes, 101, 103, 115, 117 

parasitism, 103 
Otodectes cynotis, 115, 117 
Oviparous, application of the tenn, 

219 
Oviposition, 18, 219 
O^apositor, 18 
Ovoviviparous, appHcation of the 

term, 219 
Ox bot flies, 57 

effect of bots, 62 

Ufe history, 58 

occurrence, 57 

treatment, 62 
Ox warblqs, 53, 57 
Oxyuriasis, 236 

effect, 236 

occurrence, 236 

treatment, 237 
Oxyuridffi, 222, 235 
OAyurinas, 226 
Oxyuris, 226 

cur\Tala, 235 

equi, 235 

mastigodes, 235 



Parasites, alternation of hosts in, 5, 8 
Parasites, determinate transitory, 8 

detenninate erratic, 8 

erratic, S 



fixed, 8 

heteroxenous, 8 
incidental, 8 

monoxenous, 8 
optional occasional, 8 

pennanent, 8 

stray, 8 
Parasites, development of patho- 
genicity in, 315 
Parasites, external, 9 

internal, 9 
Parasites, factors influencing injury 
by, 10, 315 

age of host, 11 

location, 10, 315 

movements, 10 

nature of food, 10 

number present, 10 
Parasites, influence upon host, 10, 315 
Parasites, systematic position of, 6 
Parasitic diseases, terms used in, 9 
Parasitism, 2, 3, 7, 315 

adaptation to, 3, 4, 315 

degeneration in, 3, 4 

factors leading to, 1, 6, 315 

forms of, 7 

functions involved in adaptation 
to, 3 

range of, 3 

reproductive function in, 4 
Parasitism, evolution of, 315 
Parthenogenesis, 15, 322 
Pathogenic Protozoa, 311, 324 

arthropods as carriers of, 23, 315 
Pediculidse, 21, 70 
Pediculosis of the cat, 79 

control, SO 

occurrence, 79 

treatment, 81 
Pediculosis of cattle, 74 

control, SO 

indications of, 75 

location, 75 

treatment, SI 



372 



INDEX 



Pediculosis of the dog, 7S 

control, 80 

effect, 78 

location, 78 

treatment, 81 
Pediculosis of the goat, 77 

control, 80 

effect, 77 

occurrence, 77 

treatment, 80 
Pediculosis of the hog, 77 

control, 80 

effect, 77 

occurrence, 77 

treatment, 81 
Pediculosis of the horse, 72 

control, 80 

indications of, 73 

location, 73 

treatment, 80 
Pediculosis of mammals, 71 

compUcations, 71 

effect, 72 

indications of, 72 

predisposing factors, 71 

treatment, 80 
Pediculosis of man, 79 
Pediculosis of poultrj', 82 

control, 88 

dust bath in, 88 

effect, 82 

indications of, 82 

occurrence, 82 

parts attacked, 82 

sodium fluoride in treatment of, 
88 

treatment, 88 
Pediculosis of the sheep, 76 

control, 80 

occurrence, 77 

treatment, 80 
Pediculosis, control Tand treatment, 80 
Pediculus capitis, 79 

corporis, 79 



hmnanus, 79 

vestimenti, 79 
Permanent parasites, 8 
Pharyngeal filariasis of the hog, 247 
Philopteridae, 21, 71 
Philopterus cygni, 86 

icterodes, 84 
Phthiriasis, 71, 79 
Phthirius inguinalis, 79 

pubis, 79 
Physocephalus sexalatus, 252, 253 
Phytoparasites, 7 
Piroplasma bigeminum, 313, 347 
Plasmodium, 313, 318 

falciparum, 318 

malarise, 318 

praecox, 318 

\avax, 318 
Platyhehninthes, 155, 157 

classification of, 155, 157 
Plerocercoid, 173, 195 
Polystomeae, 156 
Polyzoa, 155, 159 
Pork measles, 174, 195, 199 

degeneration of cyst, 202 

development, 202 

diagnosis, 202 

influence of temperature upon larvse, 
202 

location and appearance of cysts, 
201 

method of infection, 201 

occurrence, 200 

STOaptoms, 202 

vitality of lari'se, 202 
Pork tapeworm, 195, 199 
Poultry mite, 98 

control, 9 

development, 99 

effect, 99 

habits, 98 

occurrence, 98 

reproduction, 99 
Predaceous animals, 3, 9 



INDEX 



373 



Protozoa, 311 

carj'ozoie, 322 

ccElozoic, 322 

colonization of, 311 

cji;ozoic, 322 

differentiation from Metazoa, 311 

enterozoic, 322 

hematozoic, 322 

investigations as to pathogenicity, 
313, 315 

investigations as to pathogenicitj' in 
the United States, 314 

natural classification of, 322 

parasitism, 313 

pathogenicit}', 313, 315 

pathogenic classificarion of, 322 

specialization in, 311 
Protozoa, classification of, 322 
Protozoa, methods of reproduction in, 
313, 318, 327, 329, 336, 337 

asexual method, 318, 319, 337 

multipUcative cycle, 318, 319, 337 

propagative cycle, 318, 320, 337- 

sexual method, 318, 320, 337 

sporulation, 318, 319, 320, 336, 337 
Pseudopodia, 312, 324 
Psoroptes, 101, 102 

parasitisin, 102 

species of, 103 

varieties, 103 
Psoroptes communis. 103 

var. bo\-is, 103, 113 

var. cuniculi, 103, 118 

var. equi, 103, 108 

var. o^•is, 103, 109 
Psoroptic scabies of cattle, 113 

course, 113 

sjTnptoms, 113 

treatment, 120, 128 
Psoroptic scabies of the goat, 113 
Psoroptic scabies of the horse, 108 

lesions, 108 

transmission, 108 

treatment, 120, 129 



Psoroptic scabies of the rabbit, 118 

course, 118 

symptoms, 119 

treatment, 120, 131 
Psoroptic scabies of the sheep, 109 

after-treatment, 128 

com-se, 110 

historical, 110 

lesions, 110 

prognosis, 110 

SjTnptoms, 110 

treatment, 120, 124 
Pubic louse, 79 
Pulex irritans, 65 

serraticeps, 65 
Pulicidse, 21, 65 
Pulmonary strongylosis of the cat, 262 

sj-mptoms, 262 
Pupation, 19 
Pyrosoma bigeminmn, 313 

R 

Red bugs, 99 

Red dysenterj' of cattle, 343 

Red mange of the dog, 104, 116 

Red-tailed bot fly, 57 

Remora, 2 

Reproduction, o\-iparous, IS, 219 

ovo-\-iparous, 18, 219 

pupiparus, 4, 18 

n\-iparous, IS, 219 
Respiratory mite of fowl, 134 
Rhipicentor, 142 
Rhipicephalus, 142 
Rhizopoda, 322, 324 

reproduction in, 324 
Rhvnchobdellidffi, 308 



Sarcocystis l.iertrami. 351 
blanchardi. 351 
miescheriana. 351 
tenella. 351 



374 



INDEX 



Sarcophaga sarracenise, 52 
Sarcoptes, 101 

parasitism, 102 

species of, 102 

varieties, 102 
Sarcoptes minor var. cati, US 

minor var. cimiculi, US 

mutans, 132 
Sarcoptes scabiei, 102 

var. bo\is, 114 

var. canis, 115 

var. equi, 104 

var. ovis, 112 

var. suis, 114 
Sacroptic mange, 101, 102 

of cattle, 114 

of the dog, 115 

of the goat, 113 

of the hog, 114 

of the horse, 104 

of the sheep, 112 
Sarcoptida-, 96, 101 
Sarcosi)oridia, 323, 336, 350 

(le\elojiment, 350 

muscles conmionly invaded, 350 

l)arasitism, 3.50 

jiathologic importance, 351 

theory as to source and mode of 
infection, 351 

toxicity, 351 
Sarcosporidio.sis, 350 

mode of infection, 352 
Sarcosporidiosis of cattle, 351 

of the horse, 351 

of mice, 352 

of the pig, 351 

of the sheep, 351 
Scabies, 96 
Scab mites, 94, 96 
Scaly leg of poultry, 132 
Schistosoma bo\'is, 16S 
Schistosomida', 1.57 
Schizogony, 31S, 319, .337 
Sclerostomiasis, 288 



Sclerostomum edentatmn, 289 

equinum, 288 

hypostommii, 287 

tetracanthimi, 289 

vulgare, 289 
Scorpion, 94 
Screw worm fij', 50 

development, 50 

effect, 50 

occurrence, 50 

protection from, 51 

reproduction, 50 

treatment, 51 
Sea anemone and hermit crab, 

mutualism of, 2 
Septicemia of chicks, 345 
Setaria labiato-papillosa, 244 
Sheep bot fly, 62 

effect of bots, 63 

life history, 62 

occurrence, 62 

prevention, 64 

treatment, 64 
Sheep measles, 174, 195, 203 
Sheep measles, muscular, 203 

control, 204 

derivation, 203 

development, 204 

economic importance, 204 

occurrence, 203 
Sheep measles, visceral, 203 

control, 203 

development, 203 

method of infection, 203 

occurrence, 203 

relation to food sanitation, 203 

sjTnptoms, 203 
Sheep staggers, 204 
Sheep "tick," 4, 47 

control, 48 

effect, 48 

life history, 4, 47 

occurrence, 47 

treatment, 48 



INDEX 



375 



Simplicity, primitive and degenera- 
tive, 3 
Simuliidae, 20, 31 
Simiilium pecuarum, 32 
Siphonaptera, 21, 65 
Siphunculata, 21, 70 
Sleeping sickness, 46, 314 
Southern cattle fever, 145, 313, 347 
Southern cattle tick, 144, 145, 347 
Spider, 94 
Spinose ear tick, 140 

development, 141 

effect, 141 

habits, 141 

occurrence, 141 
Spirocheta gaUinarimi, 327 

marchouxi, 327 

theileri, 316 
Spirochetida, 315, 322, 327 

as blood parasites, 315, 316 

evolution of pathogenicity in, 315 

pathogenicity, 315, 327 

transmission, 316 
Spirochetosis, 315, 327 

of fowl, 327 
Spiroptera megastoma, 245 

microstoma, 246 

sanguinolenta, 250 

scutata, 246 

sexalata, 252 

strongyUna, 251 
Spirura, 227 
Spiruridfe, 227 
Spirurinae, 227 

Splenic fever of cattle, 145, 313, 347 
Sporogony, 318, 320, 337 
Sporozoa, 323, 336 

relationship to other fonns, 336 

reproduction in, 318, 322, 336, 337 
Stable fly, 39, 332 

control, 40 

effect, 40 

life liistory, 39 

occurrence, 40 



protection from, 41 

relation to infectious diseases, 40 
332 
Staggers of sheep, 204 
Stegomya calopus, 29 

fasciata, 29 
Stephanurus deutatus, 295 
Sting, insect, 18 
Stomach worms, pasture rotation 

in eradication of, 277 
Stomach worms of cattle, 272 

of the goat, 268 

of the sheep, 268 
Stomoxj's calcitrans, 39, 315, 332 
Stray parasites, 8 
Strongj'lea?, 280 
Strongyles of the respiratory system, 

255, 256 
Strongj'UdEe, 223, 255 
parasitism of, 255 
Strongylinffi, 223, 280 
Strongyloidea, 226 
Strongjdosis, 255 

bronchial, 256 

gastric, 268 

intestinal, 268, 280 

pulmonary, 256 

renal, 295, 296 

vascular, 289 
Strongjdosis, bronchial and pulmonary 

of cattle, 259 

of the goat, 256 

of the horse, 261 

of the pig, 260 

of the sheep, 256 
Strongylosis of the intestines of the 

cat, 291 
Strongylosis of the intestines of the 
dog, 291 

development, 292 

occurrence, 292 

post-mortem appearance, 292 

STOiptoms, 292 

treatment, 293 



376 



INDEX 



Strongylosis of the intestines of the 
horse, 288 

development, 289 

post-mortem ajipearance, 290 

SMiiptoms, 290 

treatment, 291 
Strongj'losis of the large intestine of 

the goat, 287 
Strongj-losis of the large intestine of 
the sheep, 287 

occurrence, 288 
Strongj-losis, jiulmonarv of the clog, 
261 

of the cat, 262 
Strongj-losis, tracheal, of poultry, 293 
Strongylus, 226, 255 

annatus, 288 

amfieldi, 261 

cajjillaris, 258 

eohibrifonnis, 271 

oontortus, 268 

curticei, 268 

edentatus, 289 

equinus, 288 

filaria, 256 

filicoUis, '27'.i 

instahilis, 271 

micixirus, 259 

oncophora, 275 

ostertagi, 272 

paradoxus, 260 

pusillus, 262 

mfescens, 257 

vasorum, 261 

\entricosus, 268 

vulgaris, 255, 289 
Strongyl wonns, importance of, 255 

infestation, conditions fa\-oring, 255 
Struggle for existence, 1 
Subcutaneous mite of fowl, 134 
Summaries on development of Texas 

fever tick, 149, 150 
Surra, 314, 315, 332 

course, 332 



flies as carriers of, 314, 315, 332 

infection, 332 

occurrence, 332 

s>-mptoms, 332 
SjTnbiosis, 2, 7 

phases of, 2 
SjTnbiotes, 103 

communis, 103 
Syngameae, 281 
Syngamosis, 293 
Syngamus, 281, 294 

bronchialis, 293, 294 

trachealis, 293, 294 
Sjaiopsis of tapewonn larvae, 194 
SjTithetocaulus abstrusus, 262 

capillaris, 258 

rufescens, 257 



Tabanidte, 20, 35, 332 
Tabanus atratus, 35 

lineola, 36 

striatus, 332 
Table of principal tapewonns and 

larvae, 173 
Taenia, 173 
Taenia alba, 176 

cesticillus, 190 

ccenurus, 179 

crassicollis, 184 

cucumerina, 178 

echinobothrida, 191 

echinococcus, 181, 210 

expansa, 176 

fimbriata, 174, 176, 177 

hydatigena, 178, 195, 203 

mamillana, 175 

marginata, 178 

mediocanellata, 195 

ovis, 204 

perfoliata, 174 

plicata, 175 

proglottina, 191 



INDEX 



377 



saginata, 170, 174, 195 

serialis, 179 

serrata, 179 

solium, 174, 195 

teniaefonnis, 184 

tetragona, 190 
Tseniasis, 172, 174 

prevention, 187 

treatment in general, 186 
TEeniidffi, 20, 159, 170 

life history of, 169, 171 
Tail scab of cattle, 113 
Tapeworm larvse, 173, 174, 194 

synopsis of, 194 
Tapewoims, 5, 169 

elassification of, 159, 173 

cystic fomas, 173, 194 

degeneration of, 5, 172 

parasitism of, 5, 172 
Tapewonns of the cat, 184 

occurrence, 184 

symptoms, 184 

treatment, 188 
Tapewonns of cattle, 176 

occurrence, 177 

sjmiptoms, 177 

treatment, 188 
Tapewonns of chickens, 189 

control, 192 

diagnosis, 192 

investigations as to, 189 

occurrence, 189, 191 

sjonptoms, 191 

treatment, 192 
Tapewonns of the dog, 178 

diagnosis, 183 

occurrence, 181 

pathogenesis, 182 

prevention, 187 

relation to human infection, 183 

sjinptoms, 181 

treatment, 186 
Tapewonns of the horse, 174 

occurrence, 175 



symptoms, 175 

treatment, 188 
Tapeworms of the rabbit, 185 

diagnosis, 185 

occurrence, 185 
Tapeworms of the sheep, 176 

occurrence, 177 

symptoms, 177 

treatment, 188 
Telosporidia, 336 
Tetrameres fissispina, 254 
Texas fever, 11, 145, 313, 347 

acute type, 349 

chronic type, 349 

development of the piroplasma, 348 

distribution, 348 

infecting organism of, 347 

influence of climate upon, 349 

occurrence, 348 

period from exposure to develop- 
ment, 348 

prevention, 350 

relationship of the tick to transmis- 
sion, 145, 314, 347 

symptoms, 349 

treatment, 350 
Texas fever tick, 11, 144, 145, 314, 347 

losses occasioned by, 151 

progress in eradication of, 152 

publications relative to, 145 
Texas fever tick, life history of, 148, 347 

adult period, 150 

hatching period, 148 

incubation period, 148 

lar\'al period, 150 

longevity period, 149 

nonparasitic development, 148 

njTiiphal period, 150 

o\-iposition period, 148 

parasitic development, 149 

preo\'iposition period, 148 

smmnary of nonjjarasitic periods, 
149 

sunmiary of parasitic jieriods, 150 



378 



INDEX 



Thom-headed womi, 306 
Thorn-headed \vonn of the hog, 30'i 

hfe liiston-, 306 

occurrence, 306 

pathogenesis, 306 

s\-mptoms, 306 

treatment, 307 
Thysanosoma actinioides, 174, 176, 

* 177 
Tick fever, 365, 145, 313, 347 
Ticks, 136 

classification of, 136 

stages in development of. 139, 145 

structure of, 136 
Tick, Texas fever, 144, 145, 314, 

347 
Toxascaris limbata, 238 

marginata, 238 
Toxins, parasitic, 11, 174, 220 
Tracheal injections, 265 
Tracheal strong>-Iosis of fowl, 293 

development, 294 

lesions, 294 

occurrence, 294 

prevention, 295 

sjinptoms, 294 

treatment, 295 
Transmigration, 8 
Trematoda, 156, 157 
Tricliina spiralis, 220, 299, 301 
Tricliinella, 225 
Trichiiiella spiralis, 220, 299, 301 

degeneration of cyst of, 303 

development of cyst of, 302 

life history, 302 

location of cysts of, 303 

migration, 220, 302 
Trichinellidff, 224. 299 
TricliinelliniP, 225 
Trichinelloidea, 225 
Trichinosis, 220, 301 

intestinal, 302 

method of infection, 302, 304 

muscular, 302 



occurrence, 301, 304 

prophylaxis, 305 

sjanptonis in the liog, 304 

treatment, 305 
Trichinosis in man, 304 
Trichocephalus affinis, 299 

crenatus, 299 

depressiusculus, 300 
Trichodectes climax, 77 

equi, 73 

latus, 78 

parumpilosus, 73 

pilosus, 73 

scalaris, 75 

sphoerocephalus, 76 

subrostratus, 79 
Trichostrongylidte, 226 
Trichostrongylinte, 223, 26S 
Tricliostrongj'lus, 226 

instabilis, 271 
Trichurince, 225 
Trichuris, 225 

crenatus, 299 

depressiusculus, 300 

ovis, 299 
Trinoton lituratum, 86 

luridmn, 84 
Truiotum lituratum, 86 

luridum, 84 
Triodontophorus, 281 
Trombidiidfe, 96, 99 
Troml>idium holosericeum, 100 
Tropisurus fissispinus, 254 
Tn'])anoplasma, 328 
Tryi)anosoma, 328 

americanum, 336 

brucei, 314, 330 

eciuinum, 332 

equiperdum, 333 

evansi, 314, 332 

gambiense, 314 

lewisi, 314 

theileri, 329 
Trv-panosomatida, 322, 328 



INDEX 



379 



Tiypanosomes, 314, 328 

classification of, 322, 328 

morphology of, 328, 329 

parasitism of, 314, 329 

reproduction, 329 

transmission, 314, 329 

transmission by flies, 45, 314, 329 
Trypanosomas, flies as carriers of, 
45, 314, 329 

leeches as carriers of, 314 

lice as carriers of, 314 

mosquitoes as carriers of, 314 
Trypanosomiasis, 11, 45, 314, 328 

human, 46, 314 

investigations bj' Bruce, 45, 314, 330 
Tsetse flies, 44, 314, 330 

control, 43 

method of reproduction, 44 

relationship to trj'^panosomiasis, 45, 
314, 330 
Tsetse fly disease, 44, 314, 330 

investigations by Bruce, 44, 314, 
330 
Tunicata, 3 
Tumsick, 204 
Typhoid fever, 11, 



U 



Uncinaria canina, 291 
cernua, 293 
radiata, 293 
stenocephala, 292 
trigonocephala, 291 



Vermes, 155 

Vermicides, use and action of, 121, 1S6 
Vennifuges, use and action of, 121, 186 
Verminous bronchitis and pneumonia 
of cattle, 259 

of cliildren, 231 

of the goat, 256 

of the horse, 261 

of the pig, 231, 260 

of the sheep, 256 
Vi-\dparous, application of the term, 
219 

W 

Warble flies, 53, 57 
White diarrhea of chicks, 345 
Wood tick, 143 
Wonns, 155 

classification of, 155, 157, 173 



Uncinaria, ^^281 
Uncinariasis, 291 



Zooparasites, 8 



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